N = int(input())
Y = sorted(map(int, input().split()))

if N == 2:
    print(Y[1] - Y[0])
    exit()

dp = [10 ** 9] * N
dp[1] = Y[1] - Y[0]
dp[2] = Y[2] - Y[0]
for i in range(3, N):
    dp[i] = min(dp[i - 2] + Y[i] - Y[i - 1],
                dp[i - 3] + Y[i] - Y[i - 2])
print(dp[-1])