121

count = int(input())
gvozd = sorted(list(map(int, input().split())))
delta = [gvozd[i + 1] - gvozd[i] for i in range(count - 1)]
#print(delta)
#print(gvozd)
minLen=[int() for i in range(count-1)]
minLen[0]=delta[0]
if count>2:
  minLen[1]=delta[0]+delta[1]
if count>3:
  minLen[2]=delta[0]+delta[2]
for last in range(3,count-1):
  minLen[last]=min(minLen[last-2]+delta[last],minLen[last-3]+delta[last-1]+delta[last])

print(minLen[-1])