#include <algorithm>
#include <bitset>
#include <cassert>
#include <complex>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <typeinfo>
#include <utility>
#include <vector>
#include <array>
#include <chrono>
#include <random>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;Scan(__VA_ARGS__);
template<typename T> void Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void Scan(First& first, Rest&...rest) { std::cin >> first; Scan(rest...); }
#define OUT(d) std::cout<<d;
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<d;
#define SOUT(n, c, d) std::cout<<std::setw(n)<<std::setfill(c)<<d;
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<int(n);++i)
#define RREP(i, n) for(int i=(n)-1;i>=0;--i)
#define PAIR std::pair<int, int>
#define IN(a, x, b) (a<=x && x<=b)
#define IN2(a0, y, a1, b0, x, b1) (a0<=y && y<a1 && b0<=x && x<b1)
#define SHOW(d) {std::cout << #d << "\t:" << d << "\n";}
#define SHOWVECTOR(v) {std::cout << #v << "\t:";for(const auto& i : v){std::cout << i << " ";}std::cout << "\n";}
#define SHOWVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout << j << " ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout<<'('<<j.first<<", "<<j.second<<") ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR(v) {for(const auto& i:v){std::cout<<'('<<i.first<<", "<<i.second<<") ";}std::cout<<"\n";}
#define CHECKTIME(state) {auto start=std::chrono::system_clock::now();state();auto end=std::chrono::system_clock::now();auto res=std::chrono::duration_cast<std::chrono::nanoseconds>(end-start).count();std::cerr<<"[Time:"<<res<<"ns  ("<<res/(1.0e9)<<"s)]\n";}
#define SHOWQUEUE(a) {std::queue<decltype(a.front())> tmp(a);std::cout << #a << "\t:";for(int i=0; i<static_cast<int>(a.size()); ++i){std::cout << tmp.front() << "\n";tmp.pop();}std::cout << "\n";}

//#define int ll
using ll = long long;
constexpr int INFINT = 1 << 30;
constexpr ll INFLL = 1LL << 60;
constexpr double EPS = 0.0000001;
constexpr int MOD = 1000000007;

/*

(1) c1 = p1      + p2
(2) c2 = p1*z1   + p2*z2
(3) c3 = p1*z1^2 + p2*z2^2
(4) c4 = p1*z1^3 + p2*z2^3

z1 + z2 =: A, z1*z2 =: B とおく。

(1)*(z1*z2) + (3)は、
    c1*z1*z2   = p1*z1*z2 + p2*z1*z2
+)  c3         = p1*z1*z1 + p2*z2*z2
 -------------------------------------------
 c1*z1*z2 + c3 = p1*z1(z1+z2) + p2*z2(z1+z2)
               = (z1+z2)(p1*z1 + p2*z2)
			   = (z1+z2)c2
     c1*B + c3 = c2*A


(2)*(z1*z2) + (4)は、
    c2*z1*z2   = p1*z1*z1*z2 + p2*z1*z1*z2
+)  c4         = p1*z1*z1*z1 + p2*z2*z2*z2
 -------------------------------------------------
 c2*z1*z2 + c4 = p1*z1*z1(z1+z2) + p2*z2*z2(z1+z2)
               = (z1+z2)(p1*z1*z1 + p2*z2*z2)
               = (z1+z2)c3
     c2*B + c4 = c3*A

より、
(5)  c1*B + c3 = c2*A
(6)  c2*B + c4 = c3*A
を解く。

(5)を変形して、
 c1*B = c2*A - c3
    B = (c2*A - c3)/c1 ... (7)

(6)に代入して、
  c2*(c2*A - c3)/c1 + c4 = c3*A
 c2*c2*A - c2*c3 + c1*c4 = c1*c3*A
       (c1*c3 - c2*c2)*A = c1*c4 - c2*c3
	                   A = (c1*c4 - c2*c3)/(c1*c3 - c2*c2)

(7)に代入して、
B = (c2*(c1*c4 - c2*c3)/(c1*c3 - c2*c2) - c3)/c1

今、z1、z2を解とするような2次方程式
  (X - z1)(X - z2) = 0
を考えると、
  X^2 - (z1+z2)X + z1*z2 = 0
  X^2 -    A   X +   B   = 0

となる。このときの判別式Dは
D = A^2 - 4B
より、
A^2 - 4B < 0、すなわち A^2 < 4Bのとき、
z1、z2は虚数となる。
それ以外は、z1、z2は実数となる。

*/

int main() {
	INIT;
	VAR(int, c1, c2, c3, c4);
	double A = 1.0 * (c1*c4 - c2*c3) / (c1*c3 - c2*c2);
	double B = (c2*A - c3) / c1;
	OUT(((A*A < 4 * B) ? 'I' : 'R'))BR;
	return 0;
}