Problem:
Score : 200 points

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.

Sample Input 1

5 3 3
1 2 4

Sample Output 1

1

The optimal solution is as follows:

First, travel from Square 3 to Square 4. Here, there is a toll gate in Square 4, so the cost of 1 is incurred.

Then, travel from Square 4 to Square 5. This time, no cost is incurred.

Now, we are in Square 5 and we have reached the goal.

In this case, the total cost incurred is 1.

Sample Input 2

7 3 2
4 5 6

Sample Output 2

0

We may be able to reach the goal at no cost.

Sample Input 3

10 7 5
1 2 3 4 6 8 9

Sample Output 3

3

Solution in Pascal (FPC 2.6.2) (judge verdict: Accepted)

program Project1;
     
{$APPTYPE CONSOLE}
     
uses
  SysUtils;
var
  a,h,w,i,j,count,count2,x,y,sw,m,n,b,c,soeji,sum,max,k:Integer;
  l:array of Integer;
  s,s123,s1,s2,s3:string;
  al:string = 'abcdefghijklmnopqrstuvwxyz';
  tf,tfl,tfr:Boolean;
begin
  try
    { TODO -oUser -cConsole メイン : ここにコードを記述してください }
    Read(n);
    Read(m);
    Readln(x);  
    count :=0;
    count2:=0;
    max   :=0;

    for i := 0 to m-1 do begin
      Read(a);
      if a>x then
        Inc(count)
      else
        Inc(count2);
    end;

    Readln;
    Writeln((count+count2-abs(count-count2))div 2);

    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.