#include <iostream>
#include <string>
using namespace std;
int main()
{
	string ar[3];
	cin >> ar[0] >> ar[1] >> ar[2];
	if (ar[0] == "RED")
	{
		if (ar[1] == "RED") cout << "RED" << endl;
		else
		{
			if (ar[2] == "RED") cout << "RED" << endl;
			else cout << "BLUE" << endl;
		}
	}
	else
	{
		if (ar[1] == "BLUE") cout << "BLUE" << endl;
		else
		{
			if (ar[2] == "BLUE") cout << "BLUE" << endl;
			else cout << "RED" << endl;
		}
	}
	return 0;
}