When I first saw this problem, I thought I would be done in 5 minutes but ended up spending 1 and 1/2 hours. Few test cases, so that you don't blow your head up !

Input: 4000 100 200 100
Output: 4000

Input: 150 400 1000 200
Output: 800

petr taxi
150  1000
550  800**
950  600
so in the example the answer is 800,not 950;
but ** in test case no 1:
petr taxi
150  1000
200  900
250  800
300  700
350  600
400  500
450**  400
the same set of sequence(rather similar)of event occurs with different answers...
plz help with this mess.....

Edited by author 10.04.2013 17:58