#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,s,d,f,g;
	cin>>a;
	s=a%10;
	d=a/10%10;
	g=a/100;
	f=s+d+g;
	cout<<f;
}

/**************************************************************
	Problem: 1733
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/