#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,g,s,b,q,a;
    cin>>n;
	g=n%10;
	s=n/10%10;
	b=n/100%10;
	q=n/1000;
	a=g+s+b+q;
	cout<<a;    
	return 0;
}


/**************************************************************
	Problem: 1390
	User: ccf
	Language: C
	Result: Compile Error
****************************************************************/