require 'openssl'

def md4(s)
 OpenSSL::Digest::MD4.hexdigest(s)
end

def brute
 i = 0
 loop do
   input = "0e#{i}"
   output = md4(input)
   puts "progress: #{input}" if (i % 100_000).zero?
   return [input, output] if md4(input)[/^0+e[0-9]+$/]
   i += 1
 end
end

puts brute