#include <bits/stdc++.h>
using namespace std;
int main()
{
    //freopen("numbergame.in","r",stdin);
    //freopen("numbergame.out","w",stdout);
    ios::sync_with_stdio(false);
	int n;
	cin>>n;
	cout<<n%9;
	return 0;
}

突然就AC了。。。