/in/foo.c: In function 'main':
/in/foo.c:14:9: warning: implicit declaration of function 'sort' [-Wimplicit-function-declaration]
         sort(a,a+n);
         ^~~~
/in/foo.c:15:9: warning: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
         memset(f,0,sizeof(f))
         ^~~~~~
/in/foo.c:15:9: warning: incompatible implicit declaration of built-in function 'memset'
/in/foo.c:15:9: note: include '<string.h>' or provide a declaration of 'memset'
/in/foo.c:16:9: error: expected ';' before 'f'
         f[0]=1;
         ^
/in/foo.c:27:13: error: expected ';' before '}' token
             }
             ^
/in/foo.c:29:9: warning: implicit declaration of function 'print' [-Wimplicit-function-declaration]
         print("%d\n",ans);
         ^~~~~