OJ Board

my code below
i still cannot find where get wrong
anyone can help me or give me some tips
or some key test case
point what's wrong with my code
THX

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

int main ()
{
int n;
while ( cin >> n )
{
if ( n == 0 ) return 0 ...