#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.precision(10);
  cout << fixed;
  int base;
  cin >> base;
  string s;
  cin >> s;
  vector<long long> dp(s.size() + 1);
  dp[0] = 0;
  long long MAX = 1e18;
  for (int i = 0; i < s.size(); i++) {
    dp[i + 1] = MAX;
    for (int j = 0; j <= i; j++) {
      long long number = 0;
      bool b = true;
      for (int k = j; k <= i; k++) {
        if (k == j && k != i && s[k] == '0') {
          b = false;
          break;
        }
        if (number > (MAX + '0' - s[k] + 9) / 10) {
          b = false;
          break;
        }
        number = 10 * number + s[k] - '0';
      }
      if (b && number < base) {
        if (dp[j] <= (dp[i + 1] - number + base - 1) / base) {
          dp[i + 1] = min(dp[i + 1], dp[j] * base + number);
        }
      }
    }
  }
  cout << dp.back() << endl;
  return 0;
}
