import sys N = input().split() n = int(N[0]) k = int(N[1]) mas = [int(i) for i in input().split()] mas.sort() d = 0 i = 0 b = 10**6 y = 0 res = 0 for a in range(n-1): d = mas[a + 1] - mas[a] i = d - k if i < 0: i *= -1 if i < b: b = i y = a for a in range(y, 0, -1): if mas[a] - mas[a-1] != k: res += mas[a] - mas[a-1] - k mas[a-1] = mas[a] - k for a in range(y, n-1): if mas[a + 1] - mas[a] != k: res += mas[a+1] - mas[a] - k mas[a+1] = mas[a] + k print(res) sys.exit()