#include<bits/stdc++.h>
using namespace std;
int main()
{
	char a[201];
	cin>>a;
	int sum;
	for(int i=0;i<strlen(a);i++){
		sum+=a[i]-'0';
	}
	cout<<sum;
	


	return 0;
}

/**************************************************************
	Problem: 1115
	User: hbq
	Language: C++
	Result: Wrong Answer
****************************************************************/