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

/**************************************************************
	Problem: 1119
	User: LYY001
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/