F# program to find GCD of two Numbers

Program

open System
let rec gcd a b =
    if b = 0 then a
    else gcd b (a % b)
Console.Write("Enter the first number:\t")
let a = Int32.Parse(Console.ReadLine())
Console.Write("Enter the second number:\t")
let b = Int32.Parse(Console.ReadLine())
Console.WriteLine("GCD of given two numbers is:\t{0}" , gcd a b) 

Output

Enter the first number: 1449
Enter the second number:        14
GCD of given two numbers is:    7