#include <bits/stdc++.h>
	using namespace std;
	int main(){
		int a,b=0;
		cin>>a;
		while(a!=0){
			b+=a%10;
			a/=10; 
		} cout<<b;
	}
	
	
	
	
	
	
	
	
	 
/**************************************************************
	Problem: 1119
	User: zhuangwenya
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/