N = int(input())
A = sorted(list(map(int, input().split())))
dp = [float('inf')]*N
dp[1] = A[1]-A[0]
if N > 2:
    dp[2] = A[2]-A[0]
for i in range(3, N):
    dp[i] = min(dp[i-3]+A[i]-A[i-2], dp[i-2]+A[i]-A[i-1])
print(dp[-1])