Untitled

You have a man standing at position P on a line. The length of the line is M. In the next N lines his movements are given(in the order he should make them), he can either move left or right but he can't move to the left more than 0 and to the right more then M. We shoud find the rightmost position in which he can be after the N movements.

 

in:         out:

5 10        10

3

5 3 7

 

in:         out:

8 20        -1

4

15 2 9 10

 

first example: the start position is 5 and you should make 3 movements. You can achive the rightmost position if you make 5 steps left (5-5=0), then 3 steps right (0+3=3) and then 7 steps right (3+7=10).

 

second example: the start position is 8 and the stage length is 20. Because the first step is 15 if we can't go left (8-15<0) and we can't go right (8+15>20) so the result is -1.