#include<bits/stdc++.h> 
using namespace std;
int main(){
	int n,m,g,s,b;
	cin>>n;
	g=n%10;
	s=n/10%10;
	b=n/100;
	m=g+s+b;
	printf("%d",m);
}
/**************************************************************
	Problem: 1716
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:42 ms
	Memory:2072 kb
****************************************************************/