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

# z1+z2
p = c1 * c4 - c2 * c3
q = c1 * c3 - c2 ** 2

# z1*z2
r = c2 * c4 - c3 ** 2
s = c1 * c3 - c2 ** 2

# t^2-(z1+z2)t+z1*z2=0
if r != 0:
	D = p * p * s - 4 * q * q * r
	if s < 0: D *= -1
	if D >= 0:
		print 'R'
	else:
		print 'I'
else:
	print 'R'