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 C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>

/*
	入力例：
	3
	1 1 3
*/
int main(){
	int iDataNum,st,sx,sy,i;
	int ct,cx,cy;
	int strInput[2];
	for(int i=0;i<2;i++){
	 scanf("%d", &strInput[i]);
	}
	if(strInput[1]== 0){
		printf("%d",strInput[0]);
		return 0;
	}

	int strInput2[strInput[1]];
	for(int i=0;i<strInput[1];i++){
	 scanf("%d", &strInput2[i]);
	}
	
	int tmp=-1;
	  for (int i=0; i<strInput[1]; ++i) {
	    for (int j=i+1; j<strInput[1]; ++j) {
	      if (strInput2[i] > strInput2[j]) {
		tmp =  strInput2[i];
		strInput2[i] = strInput2[j];
		strInput2[j] = tmp;
	      }
	    }
	  }

	int bExist = 1;
	for(int i=1;i<=100;i++){
		bExist=1;
		for(int j=0;j<strInput[1];j++){
			if(strInput2[j]==strInput[0]-i){
				bExist=-1;
				break;
			}

		}
		if (bExist==1) {
			printf("%d",strInput[0]-i);
			return 0;
		}
		bExist = 1;
		for(int j=0;j<strInput[1];j++){
			if(strInput2[j]==strInput[0]+i){
				bExist=-1;
				break;
			}

		}
		if (bExist==1) {
			printf("%d",strInput[0]+i);
			return 0;
		}
	}

	printf("%d",strInput[0]);

  return 0;
}