https://www.luogu.com.cn/record/100420713

#include <bits/stdc++.h>
using namespace std;

int main(){
    int l, n;
    scanf("%d%d", &l, &n);
    int maxn = 0;
    int minn = 2e9;
    for(int i = 1; i <= n; i++){
        int x;
        scanf("%d", &x);
        maxn = max(maxn, max(l-x+1, x));
        minn = max(minn, min(l-x+1, x));
    }
    printf("%d %d\n", minn, maxn);
    return 0;
}