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

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