min_instability
You are given an array a consisting of n integer numbers.
Let instability of the array be the following value: max_{i = 1}^{n} a_i - min_{i = 1}^{n} a_i.
You have to remove exactly one element from this array to minimize instability of the resulting (n-1)-elements array. Your task is to calculate the minimum possible instability.
Input
The first line of the input contains one integer n (2 ≤ n ≤ 10^5) — the number of elements in the array a.
The second line of the input contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^5) — elements of the array a.
Output
Print one integer — the minimum possible instability of the array if you have to remove exactly one element from the array a.
Examples
Input
4
1 3 3 7
Output
2
Input
2
1 100000
Output
0
Note
In the first example you can remove 7 then instability of the remaining array will be 3 - 1 = 2.
In the second example you can remove either 1 or 100000 then instability of the remaining array will be 100000 - 100000 = 0 and 1 - 1 = 0 correspondingly.
Function Signature
def min_instability (n : Nat) (arr : Array Nat) : NatTheorem Signature
def array_max (arr : Array Nat) : Nat :=
  arr.foldl (fun acc x => max acc x) 0
def array_min (arr : Array Nat) : Nat :=
  arr.foldl (fun acc x => min acc x) (arr[0]!)
def instability (arr : Array Nat) : Nat :=
  array_max arr - array_min arr
def remove_at (arr : Array Nat) (i : Nat) : Array Nat :=
  (arr.extract 0 i).append (arr.extract (i+1) arr.size)
def min_instability_prop (n : Nat) (arr : Array Nat) (out : Nat) : Prop :=
  n = arr.size ∧ 
  out = Id.run do
    let mut min_inst := instability (remove_at arr 0)
    for i in [1:n] do
      let curr_inst := instability (remove_at arr i)
      min_inst := min min_inst curr_inst
    min_inst
theorem min_instability_spec (n : Nat) (arr : Array Nat) : min_instability_prop n arr (min_instability n arr)Please log in or register to submit a solution for this challenge.