input.rb

def euclid_it a, b
         while b != 0
         	   r = a % b
         	   a, b = b, r
         end 	
    a
end	

def euclid_rec a, b
         if b == 0
         	a
         else
         	euclid_rec(b, a % b)
         end  
end	

def main
    #print "a = "
    #a = gets.to_i
    #print "b = "
    #b = gets.to_i
    #c = euclid_rec(a,b)
    #print c
    a = ARGV[0].to_i
    b = ARGV[1].to_i
    c = euclid_rec(a,b)
    p c    
end	
main