LnipLesson4

#include <algorithm>
#include <exception>
#include <iostream>
#include <string>

typedef long long ll;

int main2() {
  int n = 0;
  int base = 10;
  std::cin >> n >> base;
  std::string result;
  while (n > 0) {
    char c = char(n % base) + '0';
    n /= base;
    result += c;
  }
  std::reverse(result.begin(), result.end());
  std::cout << result << std::endl;
}

int CharToInt(char c) {
  if (c >= '0' && c <= '9') return c - '0';
  if (c >= 'A' && c <= 'Z') return c - 'A' + 10;
  if (c >= 'a' && c <= 'z') return c - 'a' + 10;
  throw std::runtime_error("Very Bad Symbol");
}

ll Str2Int(std::string& s, int base) {
  ll result = 0;
  // Схема Горнера.
//  result = (((s[0]*10 + s[1])* 10 + s[2])*10 + s[3])*10 + ... + s[l-1];
  for (int i = 0; i < s.length(); ++i) {
    result = result * base + CharToInt(s[i]);
  }
  return result;
}

int main() {
  std::string s;
  int base = 10;
  std::cin >> s >> base;

  try {
    std::cout << Str2Int(s, base) << std::endl;
  } catch (std::runtime_error& e) {
    std::cout << e.what();
  }
  return 0;
}