/in/foo.cc: In function 'int main()':
/in/foo.cc:16:15: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
  scanf("%d",&n);
               ^
/in/foo.cc: In function 'long long int half(int, int, int, long long int*)':
/in/foo.cc:13:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^