#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,h=0,y=0;
	cin>>n;
	while(n!=0){
		y=n%10;
		h=h+y;
		n=n/10
	}
	cout<<h;
}

/**************************************************************
	Problem: 1119
	User: zengyixuan
	Language: C
	Result: Compile Error
****************************************************************/