#coding: utf-8
##yuki_328
import sys

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

z1=1.0*(c2*c3-c1*c4)/(c2*c2-c1*c3)
z2=1.0*(c3*c3-c2*c4)/(c2*c2-c1*c3)

if z1*z1-4.0*z2>=0.0:
 print "R"
else:
 print "I"