n = int(input())
y = list(map(int, input().split()))
y.sort()
dp=[0]*n
dp[0]=10**10
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])