import java.util.Arrays; import java.util.Scanner;

public class ccc18s1 {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner sc = new Scanner(System.in);

    int N = sc.nextInt();   
    int[] A = new int[N];
    for (int i=0; i<N; i++) {
        A[i] = sc.nextInt();
    }
    Arrays.sort(A);
    int[] B = new int[N];
    B[0] = Integer.MAX_VALUE;
    B[N-1] = Integer.MAX_VALUE;
    for (int i=1; i<N-1;i++) {
        B[i] = (A[i+1]-A[i-1])/2.0;
    }
    Arrays.sort(B);
    System.out.printf("%.01f", B[0]);
}

}