Find the color of the k-th ball (1-index based) that will be destroyed.

Bob is playing with his ball destroyer robot. Initially, Bob has r red balls, g green balls and b blue balls. The robot will repeat the following 3-step program until there are no balls left: If there is at least one red ball available, destroy one red ball. If there is at least one green ball available, destroy one green ball. If there is at least one blue ball available, destroy one blue ball. You are given the longs r, g and b. You are also given a long k. Find the color of the k-th ball (1-index based) that will be destroyed. If the color of the k-th ball to be destroyed is red, return "RED" (quotes for clarity, returned values are case-sensitive). If the color is green, return "GREEN". If the color is blue, return "BLUE". Source : Commented by a user named bob , later i found property of TopCoder , so i have am just sharing it to learning purpose , TopCoder Inc. holds all right on the problem statement .