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

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> P;

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    vector<double> c(5);
    rep(i, 4) cin >> c[i + 1];

    double det = c[2] * (-c[2]) - (-c[1]) * c[3];
    double Z1 = ((-c[2]) * c[3] + c[1] * c[4]) / det;
    double Z2 = ((-c[3]) * c[3] + c[2] * c[4]) / det;

    double D = Z1 * Z1 - 4 * Z2;
    if (D >= 0) {
        cout << "R" << endl;
    } else {
        cout << "I" << endl;
    }
}