import sys
readline=sys.stdin.readline

N=int(readline())
Y=list(map(int,readline().split()))
Y.sort()
inf=1<<60
dp=[inf]*(N+1)
dp[0]=0
for i in range(1,N+1):
    if i>=2:
        dp[i]=min(dp[i],dp[i-2]+Y[i-1]-Y[i-2])
    if i>=3:
        dp[i]=min(dp[i],dp[i-3]+Y[i-1]-Y[i-3])
ans=dp[N]
print(ans)