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: Accepted)

number = gets.to_s.split(" ")

x = number[0].to_i
y = number[1].to_i

if x > y
  z = x % y
  z = y.gcd(z)
  puts z
end

if x < y
  z = y % x
  z = x.gcd(z)
  puts z
end

if x == y
  puts x
end