TypeError: argument 1 must be pygame.Surface, not str

background.blit(t1_lives, (70, 70)) #shows how many lives has p1
background.blit(t2_lives, (930, 70)) #shows how many lives has p2

import pygame, random, os
 
pygame.init()
 
os.environ['SDL_VIDEO_CENTERED'] = '1' #чтобы центрилизировать окно запуска
 
w = 1000
h = 1000
 
screen = pygame.display.set_mode((w, h))
background = pygame.image.load('ground.jpg') #importing image of background
 
FPS = 60
 
t1_live_cnt = "3" #счетчик жизни
t2_live_cnt = "3"
 
font = pygame.font.SysFont('Retro.ttf', 36)
t1_lives = font.render(t1_live_cnt, True, (255,255,255))
t2_lives = font.render(t2_live_cnt, True, (255,255,255))
 
background.blit(t1_lives, (70, 70)) #shows how many lives has p1
background.blit(t2_lives, (930, 70)) #shows how many lives has p2
 
clock = pygame.time.Clock() 
 
t1 = pygame.image.load('t1_up.png') #importing 1 tank
t2 = pygame.image.load('t2_up.png') #importing 2 tank
 
 
x_t1 = 70 #x coorrdinate 1 tank
y_t1 = 535 #y coordinate 1 tank
 
x_t2 = 860 #x coorrdinate 2 tank
y_t2 = 535 #y coorrdinate 2 tank
 
speed = 1
#######################
t1_up = 'up'
t1_down = 'down'
t1_left = 'left'
t1_right = 'right'
                      #directions
t2_up = 'up'
t2_down = 'down'
t2_left = 'left'
t2_right = 'right'
#######################
movement1 = False #to know when to move
movement2 = False #to know when to move
 
shoot_sound = pygame.mixer.music.load("shoot.mp3")
 
t1_bullet_x = x_t1 + 35
t1_bullet_y = y_t1
 
t2_bullet_x = x_t2 + 35
t2_bullet_y = y_t2
 
pygame.display.update()
 
t1_strike = False
 
play = True
 
while play:
    pygame.display.update()
    if movement1 == t1_up:
        t1 = pygame.image.load('t1_up.png') #rotation
        y_t1 -= speed
        t1_bullet_x = x_t1 + 35 ##
        t1_bullet_y = y_t1      ##changing direction of bullet after rotation
    if movement1 == t1_down:
        t1 = pygame.image.load('t1_down.png')
        y_t1 += speed
        t1_bullet_x = x_t1 + 35
        t1_bullet_y = y_t1 + 70
    if movement1 == t1_right:
        t1 = pygame.image.load('t1_right.png')
        x_t1 += speed
        t1_bullet_x = x_t1 + 70
        t1_bullet_y = y_t1 + 35
    if movement1 == t1_left:
        t1 = pygame.image.load('t1_left.png')
        x_t1 -= speed
        t1_bullet_x = x_t1
        t1_bullet_y = y_t1 + 35
 
    if movement2 == t2_up:
        t2 = pygame.image.load('t2_up.png')
        y_t2 -= speed
        t2_bullet_x = x_t2 + 35
        t2_bullet_y = y_t2
        if t1_strike:
            t1_bullet_y += 2
    if movement2 == t2_down:
        t2 = pygame.image.load('t2_down.png')
        y_t2 += speed
        t2_bullet_x = x_t2 + 35
        t2_bullet_y = y_t2 + 70
    if movement2 == t2_right:
        t2 = pygame.image.load('t2_right.png')
        x_t2 += speed
        t2_bullet_x = x_t2 + 70
        t2_bullet_y = y_t2 + 35
    if movement2 == t2_left:
        t2 = pygame.image.load('t2_left.png')
        x_t2 -= speed   
        t2_bullet_x = x_t2
        t2_bullet_y = y_t2 + 35
 
 
 
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            play = False
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                exit()
            if event.key == pygame.K_SPACE:
                pygame.mixer.music.play()
                t1_strike = True
                t1_bullet = pygame.draw.rect(background, (255,211,0), (t1_bullet_x, t1_bullet_y, 9, 9))
                t1_bullet_x = t1_bullet_x + 3
                pygame.display.update()
            if event.key == pygame.K_RETURN:
                t2_bullet = pygame.draw.rect(background, (255,0,0), (t2_bullet_x, t2_bullet_y, 9, 9))
                pygame.mixer.music.play()
###############################################
            if event.key == pygame.K_d:  
                movement1 = t1_right
            if event.key == pygame.K_a:
                movement1 = t1_left
            if event.key == pygame.K_w:     
                movement1 = t1_up
            if event.key == pygame.K_s:
                movement1 = t1_down
            if event.key == pygame.K_LALT:
                movement1 = False
###############################################Changes direction
            if event.key == pygame.K_RIGHT:
                movement2 = t2_right
            if event.key == pygame.K_LEFT:
                movement2 = t2_left
            if event.key == pygame.K_UP:
                movement2 = t2_up
            if event.key == pygame.K_DOWN:
                movement2 = t2_down
            if event.key == pygame.K_KP0:
                movement2 = False
###############################################
    if x_t1 > w + 60:
        x_t1 = 0 - 60
    if x_t1 < 0 -60:
        x_t1 = w + 60
    if y_t1 > w + 60:
        y_t1 = 0 - 60
    if y_t1 < 0 -60:
        y_t1 = w + 60
 
    if x_t2 > w + 60:
        x_t2 = 0 - 60
    if x_t2 < 0 -60:
        x_t2 = w + 60
    if y_t2 > w + 60:
        y_t2 = 0 - 60
    if y_t2 < 0 -60:
        y_t2 = w + 60
 
    if t1_bullet_x >= x_t2 and t1_bullet_x <= x_t2 + 70 and t1_bullet_y >= y_t2 and t1_bullet_y <= y_t2 + 70:
        t2 = pygame.image.load('explosion.png')
        pygame.mixer.music.load("crash.mp3")
        pygame.mixer.music.play()
        t2_lives = str(int(t2_live_cnt) - 1)
        background.blit(t2_lives, (930, 70))
        x_t2 = 860
        y_t2 = 535
 
    if t2_bullet_x >= x_t1 and t2_bullet_x <= x_t1 + 70 and t2_bullet_y >= y_t1 and t2_bullet_y <= y_t1 + 70:
        t1 = pygame.image.load('explosion.png')
        pygame.mixer.music.load("crash.mp3")
        pygame.mixer.music.play()
        t1_lives = str(int(t2_live_cnt) - 1)
        background.blit(t1_lives, (70, 70))
        x_t1 = 70
        y_t1 = 535
 
    screen.blit(background, (0,0))
    screen.blit(t1, (x_t1, y_t1))
    screen.blit(t2, (x_t2, y_t2))
    clock.tick(FPS)
 
    background.blit(t1_lives, (70, 70)) #shows how many lives has p1
    background.blit(t2_lives, (930, 70)) #shows how many lives has p2
 
    pygame.display.set_caption("TANK MOTHERF*CKER")
 
    pygame.display.flip()
 
 
 
pygame.quit()

t1_lives = font.render(t1_live_cnt, True, (255,255,255))

t1_lives = str(int(t2_live_cnt) - 1)

t1_lives = font.render(str(int(t2_live_cnt) - 1), True, (255,255,255))