7974. What's Next

code:

while 1: 
    a, b, c = [int(x) for x in raw_input().split()] 
    if a == 0 and b == 0 and c == 0: 
        break 

    elif b - a == c - b: 
        print 'AP', c + (b - a) 
         
    elif b/a == c/b: 
        print 'GP', c * (b/a)

# end of source code

Be Pythonic