c1, c2, c3, c4 = map(int, input().split())
if c1**2*c4**2 - 6 * c1*c2*c3*c4 + 4 * c1 * c3**3 + 4 * c2**3 * c4 - 3 * c2**2 * c3**2 < 0:
    print('I')
else:
    print('R')