package contest;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Q703 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		long c1 = ni();
		long c2 = ni();
		long c3 = ni();
		long c4 = ni();
		if(c1 == 0){
			out.println("R");
			return;
		}
		// c3=c1((c2/c1)^2-b^2)
		// b^2=(c2/c1)^2-c3/c1 ?
		// c4=c1((c2/c1)^3-3(c2/c1)b^2)
		// 3(c2/c1)b^2=(c2/c1)^3-c4/c1
		// b^2=(c2/c1)^2/3-c4/3c2
		F a = new F(c4*c1-c3*c2, 2*(c3*c1-c2*c2));
//			F br = F.mul(a, new F(c1)).sub(new F(c2)).div(new F(2));
		F b2 = F.mul(a, a);
		b2.sub(new F(2).mul(a).mul(F.sub(a, new F(c2, c1))));
		b2.sub(new F(c3, c1));
		if(b2.num > 0){
			out.println("I");
		}else{
			out.println("R");
		}
	}
	
	public static class F implements Comparable<F> {
		public long num, den;
		
		public F(){ this.num = 0; this.den = 1; }
		public F(long num){ this.num = num;	this.den = 1;}
		public F(long num, long den){ this.num = num; this.den = den; reduce();}
		
		public F reduce()
		{
			if(den == 0) {
			}else if(num == 0) {
				den = 1;
			}else {
				if(den < 0) {
					num = -num;
					den = -den;
				}
				long g = gcd(Math.abs(num), den);
				num /= g;
				den /= g;
			}
			return this;
		}
		
		public static F add(F a, F b){ return new F(a.num*b.den+a.den*b.num, a.den*b.den); }
		public static F sub(F a, F b){ return new F(a.num*b.den-a.den*b.num, a.den*b.den); }
		public static F mul(F a, F b){ return new F(a.num*b.num, a.den*b.den); }
		public static F div(F a, F b){ return new F(a.num*b.den, a.den*b.num); }
		public static F inv(F a){ return new F(a.den, a.num); }
		
		public F add(F b){ num = num*b.den+den*b.num; den *= b.den; return reduce(); }
		public F sub(F b){ num = num*b.den-den*b.num; den *= b.den; return reduce(); }
		public F mul(F b){ num *= b.num; den *= b.den; return reduce(); }
		public F div(F b){ num *= b.den; den *= b.num; return reduce(); }
		public F inv(){ long d = num; num = den; den = d; return reduce(); }
		
		protected static long gcd(long a, long b) {
			while (b > 0) {
				long c = a;
				a = b;
				b = c % b;
			}
			return a;
		}
		
		public String toString() { return num + "/" + den; }
		public int compareTo(F f) { return Long.signum(num * f.den - f.num * den); }
	}
	
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
	}
	
	public static void main(String[] args) throws Exception { new Q703().run(); }
	
	private byte[] inbuf = new byte[1024];
	private int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}