N = int(input())
A = sorted([int(i) for i in input().split()])

ans = 0
isOnly = True

for i in range(N-1):

    if A[i] == A[i+1]:
        isOnly = False

    elif isOnly:
        ans += 1
        if i == N-2:
            ans+=1
    else:
        isOnly = True
        
print(ans)