#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,s = 0;
	cin>>n;
	do{
		s += n % 10;
		n /=10; 
	}while(n !=0);
	cout<<s;
	return 0; 
}
/**************************************************************
	Problem: 1119
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/