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