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

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