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 C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>

int main(){
    int N, M, X;
    int A[110];
    int tmp;
    int sumR=0, sumL=0;
    int i;

    scanf("%d %d %d", &N, &M, &X);
    for(i=0; i<N; i++){
        A[i]=0;
    }
    A[N] = -1;
    A[X] = -1;
    for(i=0; i<M; i++){
        scanf("%d", &tmp);
        A[tmp] = 1;
    }
    for(i=0; i<X; i++){
        if(A[i]==1){
            sumL += 1;
        }
    }
    for(i=X; i<=N; i++){
        if(A[i]==1){
            sumR += 1;
        }
    }
    //printf("%d %d ", sumL, sumR);
    if(sumL<sumR){
        printf("%d", sumL);
    }else{
        printf("%d", sumR);
    }

    return 0;
}