Problem Statement

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.

Constraints

• $1 \leq N \leq 100$
• $1 \leq M \leq 100$
• $1 \leq X \leq N - 1$
• $1 \leq A_1 < A_2 < ... < A_M \leq N$
• $A_i \neq X$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M X
A_1 A_2 ... A_M

Output

Print the minimum cost incurred before reaching the goal.