#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,s;
    cin>>x;
	s=x%10+x/10%10+x/100;
	cout<<s; 
    
    
	
	
}
/**************************************************************
	Problem: 1027
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/