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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func contains(target string, list []string) bool {
	for _, r := range list {
		if target == r {
			return true
		}
	}
	return false
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()

	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}
func nextInt64() int64 {
	sc.Scan()

	i, e := strconv.ParseInt(sc.Text(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}

func nextF64() float64 {
	sc.Scan()

	i, e := strconv.ParseFloat(sc.Text(), 64)
	if e != nil {
		panic(e)
	}
	return i
}

func isInteger(x float64) bool {
	return math.Floor(x) == x
}

func Ave(s []int) int {
	val := 0
	for _, i := range s {
		val += i
	}
	return int(val / len(s))
}
func cal(i int) (sum int) {
	for i != 0 {
		sum += i % 10
		i /= 10
	}
	return
}
func max(a []int) (idx int, val int) {
	max := a[0]
	idx = 0
	for j, i := range a {
		if max < i {
			max = i
			idx = j
		}
	}
	return idx, max
}

func draw(i int, a []int) (l []int) {
	// p = a[i]
	for j := i; j < len(a); j++ {
		if j != len(a)-1 {
			a[j] = a[j+1]
		} else if j == len(a)-1 {
			a = a[:len(a)-1]
		}
	}
	return a
}
func abs(i int64) int64 {
	if i < 0 {
		return -i
	}
	return i
}

func main() {
	sc.Split(bufio.ScanWords)
	// sc.Buffer([]byte{}, math.MaxInt64)
	// a := make([][]int, 3)
	// for i := 0; i < 3; i++ {
	// 	a[i] = make([]int, 3)
	// }
	// for i := 0; i < 3; i++ {
	// 	for j := 0; j < 3; j++ {
	// 		a[i][j] = nextInt()
	// 	}
	// }

	n := nextInt()
	m := nextInt()
	x := nextInt()
	var a []int
	var cntb int
	var cntf int
	for i := 0; i < m; i++ {
		a = append(a, nextInt())
	}
	n = n
	for _, val := range a {
		if val < x {
			cntb++
		} else {
			cntf++
		}
	}

	if cntb < cntf {
		fmt.Println(cntb)
	} else {
		fmt.Println(cntf)
	}

}