#include<bits/stdc++.h>
using namespace std;
int main(){
	int g,s,b,w,a=0;
	cin>>w;
	g=w%10;
	s=w/10%10;
	b=w/100;
	a=g+s+b;
	cout<<a;
	return 0;
}
/**************************************************************
	Problem: 1119
	User: lijinkai
	Language: C++
	Result: Wrong Answer
****************************************************************/