#include<bits/stdc++.h>
using namespace std;
int main()
{
	int x=0;
	cin>>x;
	int g,s,b=0;
	g=x%10;
	s=x/10%10;
	b=x/100;
	s=g+s+b;
	cout<<s<<endl;

	return 0;
}

/**************************************************************
	Problem: 1027
	User: 21A
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/