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

	    
	
 

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