inf = 10**9
N = int(input())
Y = list(map(int, input().split()))

if N == 2 or N == 3:
    print(max(Y) - min(Y))
    exit()


Y.sort()
dp = [inf] * N
dp[1] = Y[1] - Y[0]
dp[2] = Y[2] - Y[0]
for i in range(3, N):
    dp[i] = min(dp[i], dp[i-2] + Y[i]-Y[i-1])
    dp[i] = min(dp[i], dp[i-3] + Y[i]-Y[i-2])

print(dp[N-1])