Problem:
Greatest Common Divisor

Write a program which finds the greatest common divisor of two natural numbers a and b

Input

a and b are given in a line sparated by a single space.

Output

Output the greatest common divisor of a and b.

Constrants

1 ≤ a, b ≤ 109

Hint

You can use the following observation:

For integers x and y, if x ≥ y, then gcd(x, y) = gcd(y, x%y)

Sample Input 1

54 20

Sample Output 1

2

Sample Input 2

147 105

Sample Output 2

21

Solution in Ruby (judge verdict: Time Limit Exceeded)

x, y = gets.chomp.split.map(&:to_i).sort
if x == y
	puts x
else
	div1, div2 = Array.new, Array.new
	(y % x).times do |i|
		div1.push(i+1) if (y % x) % (i+1) == 0	
	end
	(x % (y % x)).times do |i|
		div2.push(i+1) if (x % (y % x)) % (i+1) == 0
	end
	puts (div1 & div2).max
end