/in/foo.cc: In function 'long long int dfs(long long int, long long int)':
/in/foo.cc:18:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:20:18: warning: variable 'size' set but not used [-Wunused-but-set-variable]
  long long n,i,j,size,a,b,Max;
                  ^~~~