#include <iostream>
#include <sstream>
#include <cstdlib>
#include <bits/stdc++.h>
#include <algorithm>

using namespace std;
void sum(int n,long long s ){
    long long sum=0;
     while(s>0){
        int temp=s%10;
        sum+=temp;
        s/=10;
     }
     cout<<sum;
}

int main()
{
    int n;
    cin>>n;
    long long s;
    cin>>s;
    sum(n,s);
    return 0;
}