Problem:
Score : 300 points

Problem Statement

Given are an integer X and an integer sequence of length N: p_1, \ldots, p_N.

Among the integers not contained in the sequence p_1, \ldots, p_N (not necessarily positive), find the integer nearest to X, that is, find the integer whose absolute difference with X is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

1 \leq X \leq 100

0 \leq N \leq 100

1 \leq p_i \leq 100

p_1, \ldots, p_N are all distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X N
p_1 ... p_N

Output

Print the answer.

Sample Input 1

6 5
4 7 10 6 5

Sample Output 1

8

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the one nearest to 6 is 8.

Sample Input 2

10 5
4 7 10 6 5

Sample Output 2

9

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the ones nearest to 10 are 9 and 11. We should print the smaller one, 9.

Sample Input 3

100 0

Sample Output 3

100

When N = 0, the second line in the input will be empty. Also, as seen here, X itself can be the answer.

Solution in Go (1.14.1) (judge verdict: Wrong Answer)

package main

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

func main() {
	sc.Split(bufio.ScanWords)
    X := scanInt()
    N := scanInt()
    p := make([]int,N)
    for i:= 0; i<N; i++ {
    	p[i] = scanInt()
	}
	sort.Ints(p)
    aru := false
    for i:= 0; i<N; i++ {
    	if p[i] == X {
    		aru = true
		}
	}
    if !aru {
    	fmt.Println(X)
	} else {
		gosa := 1000
		number := 0
		for i:= 1; i<=100; i++ {
			value := X-i
			if value < 0 {
				value = -value
			}
			if gosa > value {
				nai := true
				for j:=0; j<N; j++ {
					if p[j] == i {
						nai = false
						break
					}
				}
				if nai {
					// fmt.Println(i)
					gosa = value
					number = i
				}
			}
		}
		fmt.Println(number)
	}
}

var sc = bufio.NewScanner(os.Stdin)
func scanInt () int{
sc.Scan()
	i,_ := strconv.Atoi(sc.Text())
	return i
}
//func scan () string{
//	return sc.Text()
//}