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

	}
	cout<<i; 
return 0;

}
/**************************************************************
	Problem: 1119
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/