Ошибка python: объект 'int' не подлежит подписке

я новичок во всем этом, и я пытаюсь сделать стрелялку. после того, как я попытаюсь запустить код, я сталкиваюсь с ошибкой TypeError: 'int' object is not subscriptable по адресу:

строка 269: collision = isCollision(enemyX[i],enemyY[i],knifeX,knifeY)

строка 118: distance = math.sqrt((math.pow(enemyX[i] - knifeX,2)) + (math.pow(enemyY[i] - knifeY,2)))

не только здесь, но почти везде в петле, если я поставлю на нее «i»

import pygame
from pygame import mixer
mixer.init()
import random
import math

#Define some colors
BLACK = (0,0,0)
WHITE = (255,255,255)

#intialize the pygame
pygame.init()

#create the screen
screen = pygame.display.set_mode((700,583))



#Caption and icon
pygame.display.set_caption("Yoshi & the rise of mushroom ")
icon = pygame.image.load("Yoshi_icon.png")
pygame.display.set_icon(icon)

#Player
playerImg = pygame.image.load("YoshiMario.png")
playerX = 370
playerY = 480
playerX_change = 0
playerY_change = 0

#Enemy
enemyImg = [] 
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 10

for i in range(num_of_enemies):
    enemyImg.append(pygame.image.load('msh1.png'))
    enemyImg.append(pygame.image.load('msh2.png'))
    enemyX.append(random.randint(0,583))
    enemyY.append(random.randint(50,150))
    enemyX_change.append(2)
    enemyY_change.append(20)


#Knife

# ready - you cant see the knife on the screen
# fire - the knife is currently moving

knifeImg = pygame.image.load('diamondsword3.png')
knifeX = 0
knifeY = 480
knifeX_change = 0
knifeY_change = 10
knife_state = "ready"

#Score

score_value = 0
font = pygame.font.Font('freesansbold.ttf',28)

testX = 10
testY = 10

#Game Over Text
over_font = pygame.font.Font('freesansbold.ttf',64)

def show_score(x,y):
    score = font.render("Score : "+ str(score_value),True,(255,255,255))
    screen.blit(score, (x, y))

def game_over_text():
    over_text = over_font.render("GAME OVER",True,(255,255,255))
    screen.blit(over_text, (150, 250))
    
def player(x,y):
    screen.blit(playerImg, (x, y))

def enemy(x,y,i):
    screen.blit(enemyImg[i], (x, y))

def fire_knife( x, y ):
    """ Start a knife flying upwards from the player """
    global knife_state, knifeX, knifeY
    knifeX = x + 16
    knifeY = y + 10
    knife_state = "fire"

def knife_hits( enemyX, enemyY ):
    """ Return True if the knife hits the enemy at the given (x,y).
        If so, prepare the knife for firing again. """
    global knife_state, knifeX, knifeY
    collision_result = False
    if ( knife_state == "fire" and isCollision( enemyX[i], enemyY[i], knifeX, knifeY ) ):
        knife_state = "ready"
        collision_result = True
    return collision_result

def draw_knife( screen ):
    """ If the knife is flying, draw it to the screen """
    global knife_state, knifeImg, knifeX, knifeY
    if ( knife_state == "fire" ):
        screen.blit( knifeImg, ( knifeX, knifeY ) )

def update_knife():
    """ Make any knife fly up the screen, resetting at the top """
    global knife_state, knifeX, knifeY, knifeY_change
    # if the knife is already flying, move it
    if ( knife_state == "fire" ):
        knifeY -= knifeY_change
        if ( knifeY <= 0 ):
            knife_state = "ready"   # went off-screen
        
def isCollision(enemyX,enemyY,knifeX,knifeY):
    distance = math.sqrt((math.pow(enemyX[i] - knifeX,2)) + (math.pow(enemyY[i] - knifeY,2)))
    if distance < 27:
        return True
    else:
        return False

#used to manage how fast the screen updates
clock = pygame.time.Clock()
font = pygame.font.Font(None,28)

frame_count = 0
frame_rate = 60
start_time = 90

#game loop
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

     

    #if keystroke is pressed check whether its right or left
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_LEFT:
            playerX_change = -2
        if event.key == pygame.K_RIGHT:
           playerX_change = 2
        if event.key == pygame.K_UP:
           playerY_change = -2
        if event.key == pygame.K_DOWN:
           playerY_change = 2
        if event.key == pygame.K_SPACE:
            if knife_state is "ready":
                knife_Sound = mixer.Sound("knife_hitwall1.wav")
                knife_Sound.play()
                # get the current x coordinate of yoshi
                knifeX = playerX
                fire_knife(playerX,playerY)
    
    if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                playerX_change = 0
            if event.key == pygame.K_UP or event.key == pygame.K_DOWN:
                playerY_change = 0

    ## -- Timer going up --
    #Calculate total seconds
    total_seconds = frame_count // frame_rate

    #divide by 60 to get total minures
    minutes = total_seconds // 60

    #use modulus (remainder) to get seconds
    seconds = total_seconds % 60

    #use python string formatting to format in leading zeros
    output_string = "Time : {0:02}:{1:02}".format(minutes, seconds)

    # Blit to the screen
    text = font.render(output_string, True, (255,255,255))
    screen.blit(text, [10,40])
 
    # --- Timer going down ---
    # --- Timer going up ---
    # Calculate total seconds
    total_seconds = start_time - (frame_count // frame_rate)
    if total_seconds < 0:
        total_seconds = 0
 
    # Divide by 60 to get total minutes
    minutes = total_seconds // 60
 
    # Use modulus (remainder) to get seconds
    seconds = total_seconds % 60
 
    # Use python string formatting to format in leading zeros
    output_string = "Time left: {0:02}:{1:02}".format(minutes, seconds)
 
    # Blit to the screen
    text = font.render(output_string, True,(255,255,255))
 
    screen.blit(text, [10,70])
 
    # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT
    frame_count += 1
 
    # Limit frames per second
    clock.tick(frame_rate)
 
    # Go ahead and update the screen with what we've drawn.
    pygame.display.flip()
            
    # RGB - Red, Green, Blue
    screen.fill((0, 255, 0))
    
    #add a wallpaper
    bgimage=pygame.image.load("Background.png")
    screen.blit(bgimage, (0, 0))

    
    # 5 = 5 + -0.1 ->5 = 5 - 0.1
    # 5 = 5 + 0.1

    # checking for boundaries of yoshi/mushroom so it doesnt go out of bounds
    playerX += playerX_change
    if playerX < 0:
        playerX = 0
    elif playerX > 645:
        playerX = 645

    playerY += playerY_change    
    if playerY < 0:
        playerY = 0
    elif playerY > 500:
        playerY = 500

    # enemy movement
    for i in range(num_of_enemies):
        
        #Game Over
        if enemyY[i]> 440:
            for j in range(num_of_enemies):
                enemyY[j] = 2000
            game_over_text()
            break
        
        enemyX[i] += enemyX_change[i]
        if enemyX[i] <= 0:
            enemyX_change[i] = 2
            enemyY[i] += enemyY_change[i]
        elif enemyX[i] > 645:
            enemyX_change[i] = -2
            enemyY[i] += enemyY_change[i]

        update_knife()                         # move the flying knife (if any)

        if ( knife_hits( enemyX[i], enemyY[i] ) ):   
            score_value += 1
            print(score_value)
            enemyX[i] = random.randint(0,735)
            enemyY[i] = random.randint(50,150)
        else:
            draw_knife( screen )               # paint the flying knife (if any)
        
        player(playerX,playerY)
        enemy(enemyX[i],enemyY[i],i)
        pygame.display.update() 

        # collision
        collision = isCollision(enemyX[i],enemyY[i],knifeX,knifeY)
        if collision:
            pop_Sound = mixer.Sound('pop.wav')
            pop_Sound.play()
            knifeY = 480
            knife_state = "ready"
            score_value += 1
            
            enemyX[i] = random.randint(0,735)
            enemyY[i] = random.randint(50,150)

        enemy(enemyX[i],enemyY[i],i)
        

    # knife movement
    if knifeY <= 0:
        knifeY = 480
        knife_state = "ready"
        
    if knife_state == "fire":
        fire_knife(knifeX,knifeY)
        knifeY -= knifeY_change
        
    playerX += playerX_change
    playerY += playerY_change
    player(playerX,playerY)
    show_score(testX,testY)
    pygame.display.update()