Score : 200 points
There are N + 1 squares arranged in a row, numbered 0, 1, ..., N from left to right.
Initially, you are in Square X. You can freely travel between adjacent squares. Your goal is to reach Square 0 or Square N. However, for each i = 1, 2, ..., M, there is a toll gate in Square A_i, and traveling to Square A_i incurs a cost of 1. It is guaranteed that there is no toll gate in Square 0, Square X and Square N.
Find the minimum cost incurred before reaching the goal.
Input is given from Standard Input in the following format:
N M X A_1 A_2 ... A_M
Print the minimum cost incurred before reaching the goal.
5 3 3 1 2 4
1
The optimal solution is as follows:
In this case, the total cost incurred is 1.
7 3 2 4 5 6
0
We may be able to reach the goal at no cost.
10 7 5 1 2 3 4 6 8 9
3