#!/usr/bin/python3
c1, c2, c3, c4 = list(map(int, input().split()))
A = (c1*c4-c2*c3)/(c1*c3-c2**2)
B = (c2*c4-c3**2)/(c1*c3-c2**2)
f = (A**2 - 4*A*B >= 0)
print("R") if f else print("I")