Nail

n = int(input())
a = [0] + sorted([int(x) for x in input().split()])
dp = []
for i in range(n+1):
  dp.append([0] * 2)

dp[2][0] = dp[2][1] = a[2] - a[1]
for i in range(3, n+1):
  dp[i][0] = dp[i-1][1]
  dp[i][1] = min(dp[i-1][0], dp[i-1][1]) + (a[i] - a[i-1])

print(dp[n][1])