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

/**************************************************************
	Problem: 1733
	User: admin
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/