c语言的五子棋游戏代码，有点问题希望能得到大佬赐教！

#include <graphics.h>      
#include <conio.h>
#include<windows.h>
#include<stdio.h>

int num=-1;
int piece[15][15];
IMAGE bgp;

void put_background()
{
 putimage(0,0,&bgp);
 putimage(240,0,&bgp);
 putimage(0,240,&bgp);
 putimage(240,240,&bgp);

}

void draw_line()
{
 setlinecolor(RED);
 for(int x=15;x<480;x+=30)
  line(x,15,x,465);
 for(int y=15;y<480;y+=30)
  line(15,y,465,y);
}

void draw_point()
{
 setfillcolor(BLACK);
 fillcircle(4*30-15,4*30-15,3);
 fillcircle(4*30-15,12*30-15,3);
 fillcircle(8*30-15,8*30-15,3);
 fillcircle(12*30-15,4*30-15,3);
 fillcircle(12*30-15,12*30-15,3);
}

void initpiece()
{
 for(int i=0;i<15;i++)
  for(int j=0;j<15;j++)
   piece[i][j]=0;
}

int change_piece(int x,int y)
{
 if(piece[x][y]!=0)
  return 0;
 else
  piece[x][y]=num;
 return 1;
}
  
void draw_piece(int m,int n)
{
 if (num==-1)
 setfillcolor(WHITE);
 else
    setfillcolor(BLACK);
 int x,y;
 x=m/30;
 y=n/30;
 if(change_piece(x,y)==0)
  return;
 fillcircle(m-(m%30)+15,n-(n%30)+15,13);
  num*=-1;
}
int check_five_piece(int x,int y)
{if(x<2 || y<2 || x>12 || y>12)
 return 0;
if(piece[x][y] == piece[x-1][y] && piece[x][y] == piece[x-2][y] && piece[x][y] == piece[x+1][y] && piece [x][y] == piece[x+2][y])
 return 1;
if(piece[x][y] == piece[x][y-1] && piece[x][y] == piece[x][y-2] && piece[x][y] == piece[x][y+1]!=0 && piece [x][y] == piece[x][y+2])
 return 1;
if(piece[x][y] == piece[x-1][y-1] && piece[x][y] == piece[x-2][y-2] && piece[x][y] == piece[x+1][y+1] && piece [x][y] == piece[x+2][y+2])
 return 1;
if(piece[x][y] == piece[x-1][y+1] && piece[x][y] == piece[x-2][y+2] && piece[x][y] == piece[x+1][y-1] && piece [x][y] == piece[x+2][y-2])
 return 1;
else return 0;
}
int check_over()
{
  for(int i = 0; i < 15; i++)
     for(int j=0;j<15;j++)
   {  if(piece[i][j] == 0)
      continue;
 if(check_five_piece(i, j) == 1)
      return 1;
  }
 return 0;

}
  
int main()
{ 
    initgraph(480, 480); 

    loadimage(&bgp, _T("background_.jpg"));
 settextcolor(RED);
 settextstyle(42, 20, _T("楷书"));
 setbkmode(TRANSPARENT);
 put_background();
 draw_line();
    draw_point();
 MOUSEMSG m;
 while(1)
 {
  m=GetMouseMsg();
  if(m.uMsg==WM_LBUTTONDOWN)
  {
   draw_piece(m.x,m.y);
  }
  if (check_over() == 1)
  {
	  if(num = 1)
		{outtextxy(180, 220, _T("结束"));
		system("pause");
		break;
		}
	  else 
	  {outtextxy(180, 220, _T("结束"));
		system("pause");
		break;
	  }
 return 0;       
  }}

为什么调试的时候会说：错误 1 error C1075: 与左侧的大括号“{”匹配之前遇到文件结束