=begin

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

What is the 10001st prime number?

=end

primes = []
numprimes = 0
checking = 1.0
while true
  checking += 1
  isprime = true
  primes.each do |p|
    qt = checking / p
    if qt == qt.truncate
      isprime = false
      break
    end
  end
  if isprime
    numprimes += 1
    primes.push checking.to_f
  end
  break if numprimes == 10001
end

print(checking)