ZOJ Problem Set - 2301
There are infinite balls in a line (numbered 1 2 3 ....), and initially all of them are paint black. Now Jim use a brush paint the balls, every time give two integers a b and follow by a char 'w' or 'b', 'w' denotes the ball from a to b are painted white, 'b' denotes that be painted black. You are ask to find the longest white ball sequence.
First line is an integer N (<=2000), the times Jim paint, next N line contain a b c, c can be 'w' and 'b'.
Two integers the left end of the longest white ball sequence and the right end of longest white ball sequence (If more than one output the small number one). All the input are less than 2^31-1. If no such sequence exists, output "Oh, my god".
Author: ZHOU, Kai
Source: ZOJ Monthly, February 2005