#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

ll val(char c){
    return c-'0';
}
int main()
{
    ll n;
    string k;

    cin >> n >> k;
    ll pos = k.size()-1;
    ll mul = 1;
    ll res = 0;
    while(pos >= 0){
        ll cu = 0;
        ll mu = 1;
        for(int i=pos+1; i<k.size() && k[i] == '0'; i++){
            mul *= n;
        }
        while(pos >= 0 && val(k[pos])*mu+cu < n){
            cu = val(k[pos])*mu+cu;
            pos--;
            mu *= 10;
        }
        res += cu*mul;
        mul *= n;
    }
    cout << res << endl;

    return 0;
}