#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    cout<<n/100+n/10%10+n%10<<endl;
    return 0;
}
/**************************************************************
	Problem: 1027
	User: wuhanyu
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/