import sequtils,strutils,math,algorithm
var
    N = stdin.readline.parseInt
    X = stdin.readline.split.map(parseInt)
    cnt : int
X.add(0)
X.add(1_000_000_007)
X.sort(cmp)
for i in 1 .. N:
    if X[i] != X[i - 1] and X[i] != X[i + 1]:
        cnt += 1
echo cnt