import strutils, sequtils, algorithm

var
  cnt = 0
  N, A = stdin.readLine.split.map parseInt

A.sort(cmp)
A.insert(0)
A.add(0)

for i in 1 ..< A.high:
  if A[i] != A[i - 1] and A[i] != A[i + 1]:
      cnt += 1

echo cnt