#include <bits/stdc++.h>
using namespace std;
int main(){
	int x,b,s,g;
	cin>>x;
	g=x%10;
	s=x/10%10;
	b=x/100%10;
	cout<<b+s+g;
	return 0;
	}
/**************************************************************
	Problem: 1027
	User: ljl2
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/