#include<bits/stdc++.h>
#define REP(x,y,z) for(int x=y;x<=z;x++)
#define FORD(x,y,z) for(int x=y;x>=z;x--)
#define MSET(x,y) memset(x,y,sizeof(x))
#define FOR(x,y) for(__typeof(y.begin()) x=y.begin();x!=y.end();x++)
#define F first
#define S second
#define MP make_pair
#define PB push_back
#define SZ size()
#define M 
void RI(){}
template<typename... T>
void RI( int& head, T&... tail ) {
    scanf("%d",&head);
    RI(tail...);
}
using namespace std;
typedef long long LL;
typedef complex<double> C;
int c1,c2,c3,c4;
double z1z2,p,a,b,b2;
bool eq(double x,double y)
{
	return fabs(x-y) < 1e-8;
}
bool check()
{
	if(c1==0) return false;
	
	p = c1/2.0;
	a = c2/2.0/p;
	b2 = z1z2 - a*a;
	if(b2<0) return false;
	b = sqrt(b2);

	////
	C z1 = C(a, b);
	C z2 = C(a, -b);
	C tmp;

	tmp = p*(z1*z1 + z2*z2);
	if( !eq(real(tmp), c3) ) return false;
	if( !eq(imag(tmp), 0) ) return false;

	tmp = p*(z1*z1*z1 + z2*z2*z2);
	if( !eq(real(tmp), c4) ) return false;
	if( !eq(imag(tmp), 0) ) return false;

	return true;
}
int main()
{
	while(~scanf("%d %d %d %d",&c1,&c2,&c3,&c4))
	{
		z1z2 = c2*c4-c3*c3;
		z1z2 /= c1*c3-c2*c2;

		puts(check()?"I":"R");
	}
	return 0;
}