#!/usr/bin/env ruby

def decode(base, string)
  data = ((0..9).to_a + ('a'..'z').to_a + ('A'..'Z').to_a) + ['+', '/']
  if base > data.size
    raise "Max base is: #{data.size}"
  end
  total = 0
  count = 0
  string.reverse.each_char do |char|
    if char =~ /^\d+$/
      char = char.to_i
    end
    index = data.index(char)
    total = total + (index * (base ** count))
    count += 1
  end
  total
end

STDIN.each_line do |line|
  puts decode(ARGV[0].to_i, line.chomp)
end