#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef complex<double> P;
typedef pair<int,int> pii;
#define REP(i,n) for(ll i=0;i<n;++i)
#define REPR(i,n) for(ll i=1;i<n;++i)
#define FOR(i,a,b) for(ll i=a;i<b;++i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define MOD (ll)(1e9+7)
#define ADD(a,b) a=((a)+(b))%MOD
#define FIX(a) ((a)%MOD+MOD)%MOD

int main(){
  // if imag: p1 == p2, z1 == conj(z2)
  double c1,c2,c3,c4;
  cin>>c1>>c2>>c3>>c4;
  if(c1!=0){
    double p1 = c1/2.0;
    double za = c2/c1;
    double zb = sqrt(za*za - c3/c1);
    complex<double> z1(za,zb),z2(za,-zb);
    complex<double> z13 = z1*z1*z1, z23 = z2*z2*z2;
    complex<double> c4i = (z13+z23)*p1;
    if(c4i.real()==c4 && c4i.imag()==0){
      cout << "I" << endl;
    }else{
      cout << "R" << endl;
    }
  }else{
    cout << "R" << endl;
  }
  return 0;
}