foo.c: In function 'dui':
foo.c:14:13: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
      else if(a[x]>=a[d])
             ^
foo.c:23:13: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
      else if(a[x]<=a[d])
             ^
foo.c: In function 'pai':
foo.c:39:13: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
      else if(a[x]>a[d])
             ^
foo.c:48:13: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
      else if(a[x]<a[d])
             ^
foo.c: In function 'main':
foo.c:59:4: error: 'for' loop initial declarations are only allowed in C99 mode
    for(int i=1;i<=m;i++)
    ^
foo.c:59:4: note: use option -std=c99 or -std=gnu99 to compile your code
foo.c:73:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for(int i=1;i<=n;i++)scanf("%d",&a[i]);
     ^
foo.c: In function 'dui':
foo.c:29:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
foo.c: In function 'pai':
foo.c:54:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^