Codeforces-492-B-Vanya_And_Lanterns

/*  BISMILLAHIR-RAHMANIR-RAHIM
 ____________________________________
|                                    |
|       SHANTO_SUST_SWE-19_029       |
|____________________________________|
*/

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>

#define debug 0

int main()
{
    long long n, l;
    scanf("%lld %lld", &n, &l);

    long long ara[n], dif[n - 1];

    long long i, j, temp, maximum = 0;

    for(i = 0; i < n; i++) scanf("%lld", &ara[i]);

    double max = 0, d, t;

    for(i = 0; i < n - 1; i++){
        for(j = i + 1; j < n; j++){
            if(ara[i] > ara[j]){
                temp = ara[i];
                ara[i] = ara[j];
                ara[j] = temp;
            }
        }
        if(debug) printf("%lld ", ara[i]);
    }
    if(debug) printf("%lld\n", ara[i]);

    for(i = 0; i < n - 1; i++){
        dif[i] = ara[i + 1] - ara[i];
        if(dif[i] > maximum) maximum = dif[i];
        if(debug) printf("%lld ", dif[i]);
    }

    if(debug) printf("\nmaximum = %lld\n", maximum);

    max = (double)maximum;

    if(debug) printf("max = %lf\n", max);

    if((2 * ara[0]) > maximum) d = ara[0];
    else d = max / 2;

    max = d;

    if(debug) printf("max = d = %lf\n", max);

    if((long long)max < (l - ara[n - 1])) d = l - ara[n - 1];

    printf("%0.10lf\n", d);


    return 0;
}

//ALHAMDULILLAH