#include <bits/stdc++.h>                 
using namespace std;
int main(){

	int n,a,s,i,b;
	cin>>n;
	a=n/10%10;
	s=n/100;
	i=n%10;
	b=s+a+i;
	cout<<b;

}

/**************************************************************
	Problem: 1027
	User: huangyaojie3
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/