/in/foo.cc: In function 'int main()':
/in/foo.cc:29:8: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d",ans);
  ~~~~~~^~~~~~~~~~
/in/foo.cc:21:24: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   scanf("%d",&f[i]),sum+=f[i];
                     ~~~^~~~~~