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

/**************************************************************
	Problem: 1716
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:24 ms
	Memory:2072 kb
****************************************************************/