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

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