foo.cpp: In function 'long long int pop_heap()':
foo.cpp:37:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cpp: In function 'int main()':
foo.cpp:55:18: warning: unused variable 'j' [-Wunused-variable]
     long long i, j;
                  ^