#include<bits/stdc++.h>
using namespace std;
int main()
{
	char a[201];
	int sum=0;
	cin>>a;
	for(int i=0;i<a[i]!='\0';i++)
	{
		sum+=(a[i]-48);
	} 
	cout<<sum;
	return 0;
}


/**************************************************************
	Problem: 1115
	User: lzc
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/