#include <bits/stdc++.h>
using namespace std;

#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define FOR(i,n,m) for (int i=n; i<(int)(m); i++)
#define INF 1000000007

typedef vector<double> vec;
typedef vector<vec> mat;
const double EPS = 1E-8;

int c1,c2,c3,c4;

vec gauss_jordan(const mat& A, const vec& b){
    int n=A.size();
    mat B(n, vec(n+1));
    REP(i,n) REP(j,n) B[i][j]=A[i][j];
    REP(i,n) B[i][n]=b[i];
    REP(i,n){
        int pivot=i;
        FOR(j,i,n){
            if(abs(B[j][i]) > abs(B[pivot][i])) pivot=j;
        }
        swap(B[i],B[pivot]);
        if (abs(B[i][i])<EPS) return vec();
        FOR(j,i+1,n+1) B[i][j]/=B[i][i];
        REP(j,n) if(i!=j) FOR(k,i+1,n+1) B[j][k] -= B[j][i] * B[i][k];
    }
    vec x(n);
    REP(i,n) x[i]=B[i][n];
    return x;
}


int main(){
    cin >> c1 >> c2 >> c3 >> c4;
    mat A(2, vec(2));
    A[0][0]=c2;A[0][1]=-c1;
    A[1][0]=c3;A[1][1]=-c2;
    vec b(2);b[0]=c3;b[1]=c4;
    vec ans=gauss_jordan(A, b);
    double za=ans[0];
    double zb=ans[1];
    if(za*za-4*zb<0) cout << 'I' << endl;
    else cout << 'R' << endl;
    
    return 0;
}