#include<iostream>
using namespace std;
int main(){
	int n,h=0;
	cin>>n;
	while(n!=0){
		h=h+n%10;
		n=n/10;
	}
	cout<<h; 
}
/**************************************************************
	Problem: 1119
	User: wngjinming
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/