#include<iostream>
using namespace std;
int main(){
	long long n,b,s=0;
	cin>>n;
	while(n!=0){
		b=n%10;
		n=n/10;
		s+=b;
	}
	cout<<s<<endl;
}

#include<iostream> using namespace std; int main(){ long long n,b,s=0; cin>>n; while(n!=0){ b=n%10; n=n/10; s+=b; } cout<<s<<endl; }