Ruby program to calculate the Highest Common Factor

num1=0
num2=0
tmp=0

print "Enter number1: ";
num1 = gets.chomp.to_i;  

print "Enter number2: ";
num2 = gets.chomp.to_i;  

while(num2 != 0)
    tmp = num1 % num2;
    num1 = num2;
    num2 = tmp;
end

print "Highest Common Factor is: ",num1;

Output:

Enter number1: 30
Enter number2: 45
Highest Common Factor is: 15