Question B (coverage problem)

B-bTime limit:1000MS Memory Limit:262144KB 64bit IO Format:%i64d &%i6 4u  

Description

Vanya walks late at night along a straight street of length l, lit by n lanterns. Consider the coordinate system with the beginning of the street corresponding to the point 0, and its end Correspondin G to the point l. Then the i-th lantern are at the point a_{I. The lantern lights all points of the the street is at the distance of the very D from it, where d is some positive number, common for all lanterns.}

Vanya Wonders:what is the minimum light radius D Should the lanterns has to light the whole street?

Input

The first line contains the integers n, l (1≤ n ≤1000, 1≤ l ≤10 9)-the number of lanterns and the length of the street respectively.

The next line contains n integers a_{i (0≤ ai ≤ l). Multiple lanterns can is located at the same point. The lanterns is located at the ends of the street.}

Output

Print The minimum light radius D, needed to light the whole street. The answer would be a considered correct if its absolute or relative error doesn ' t exceed ^-9.

Sample Input

Input

7 15
15 5 3 7 9 14 0

Output

2.5000000000

Input

2 5
2 5

Output

2.0000000000

Hint

Consider the second sample. At d = 2 The first lantern would light the segment [0, 4] of the street, and the second lantern would light Segment [3, 5]. Thus, the whole street would be lit.

#include <iostream>#include<algorithm>#include<cstdio>#include<cmath>using namespacestd;intn,l;DoubleS,t,ans,r,u;inta[1005];intMain () {CIN>>n>>l; Doublef=0;  for(intI=0; i<n; i++) Cin>>A[i]; Sort (A,a+N);  for(intI=0; i<n-1; i++) {ans=a[i+1]-A[i]; if(f<ans) F=ans; } R=f/2; S=a[0]; T= (l-a[n-1]); Doubleu=Max (s,t); Doublev=Max (U,R); printf ("%.10lf\n", v);}

Question B (coverage problem)