#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,h;
    cin>>n;
    {
    	h=n%10+n/10%10+n/100;
	}
	printf("%d",h);
}
/**************************************************************
	Problem: 1733
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/