Description
Calculate the greatest common divisor of two integers.
In mathematics, the greatest common divisor (GCD) of two or more integers, which are not all zero, is the largest positive integer that divides each of the integers. For two integers x, y, the greatest common divisor of x and y is denoted 
For example, the GCD of 8 and 12 is 4, that is,
Input
Two integers x, y
1 < x, y< 10000
Output
Output the greatest common divisor.
Don't forget to include '\n'