N = gets.to_i def prime?(n) i = 2 while i * i <= n do return false if n % i == 0 i += 1 end return n != 1 end prime = [] n = 10**5 + 1 while prime.length < 9 do prime << n if prime?(n) n += 1 end beautiful = [1] prime.each{|x| prime.each{|y| beautiful << x * y } } beautiful.sort! puts beautiful[N-1]