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


/**************************************************************
	Problem: 1027
	User: 15159808820
	Language: C++
	Result: Accepted
	Time:32 ms
	Memory:2072 kb
****************************************************************/