#include<bits/stdc++.h> 
using namespace std;
int main()
{
	int a,g,s,b,n;
	cin>>a;
	g=a%10;
	s=a/10%10;
	b=a/100;
	n=g+s+b;
	cout<<n;
    
}
/**************************************************************
	Problem: 1716
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/