c1, c2, c3, c4 = map(int, raw_input().split())

p = (c2 * c2 - c3) * 2
q = c2 * c3 - c4
r = c2 * c4 - c3 * c3
s = c1 * c3 - c2 * c2

D = p * p * s + 4 * p * q * r
if D >= 0:
	print 'R'
else:
	print 'I'