n = int(input())
y = list(map(int, input().split()))
y.sort()
inf = float('inf')
dp = [inf] * (n + 1)
dp[0] = 0

for i in range(2, n + 1):
    if i >= 2:
        cost = y[i-1] - y[i-2]
        dp[i] = min(dp[i], dp[i-2] + cost)
    if i >= 3:
        cost = y[i-1] - y[i-3]
        dp[i] = min(dp[i], dp[i-3] + cost)

print(dp[n])