#include<bits/stdc++.h>
using namespace std;
int main()
{
    int x,g,s,b;
    cin>>x;
    g=x/1%10;
    s=x/10%10;
    b=x/100%10;
    cout<<g+s+b;
	return 0;
}

/**************************************************************
	Problem: 1029
	User: ccf
	Language: C++
	Result: Wrong Answer
****************************************************************/