#include <stdio.h>

int main(){
	unsigned red = 0, blue = 0;
	if(getchar() == 'R'){
		getchar();
		getchar();
		getchar();
		if(getchar() == 'R')
			puts("RED\n");
		else{
			getchar();
			getchar();
			getchar();
			getchar();
			if(getchar() == 'R') puts("RED\n");
			else puts("BLUE\n");
		}
	}else{
		getchar();
		getchar();
		getchar();
		getchar();
		if(getchar() == 'R'){
			getchar();
			getchar();
			getchar();
			if(getchar() == 'R') puts("RED\n");
			else puts("BLUE\n");
		}else puts("BLUE\n");
	}
	return 0;
}