using System;
using System.Linq;
using System.Diagnostics;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using System.Numerics;
using Number = System.Int32;
namespace Program
{

    public class Solver
    {
        public void Solve()
        {
            var s = Console.ReadLine().Split();
            if (Console.ReadLine() != null) throw new Exception();
            if (s.Length != 4) throw new Exception();
            var a = s.Select(int.Parse).ToArray();
            if (a.Any(x => Math.Abs(x) > 5000)) throw new Exception();
            if (a[1] * a[1] == a[0] * a[2]) throw new Exception();


            decimal X = 1.0M * (a[1] * a[2] - a[0] * a[3]) / (a[1] * a[1] - a[0] * a[2]);
            decimal Y = 1.0M * (a[2] * a[2] - a[1] * a[3]) / (a[1] * a[1] - a[0] * a[2]);
            if (X * X >= 4 * Y)
                Console.WriteLine("R");
            else Console.WriteLine("I");
        }
        //public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region main
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        //Program.IO.Printer.Out.Flush();
    }
}
#endregion