#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,nn,a,b,c;
	cin>>n;
	a=n%10;
	b=n/10%10;
	c=n/100;
	nn=a+b+c;
	cout<<nn;
	return 0;
}
/**************************************************************
	Problem: 1020
	User: tangkaixuan
	Language: C++
	Result: Wrong Answer
****************************************************************/