N = int(input())
A = list(map(int, input().split()))

B = []
C = []
D = []

for i in A:
    if i not in B:
        B.append(i)
    elif i in B:
        C.append(i)
        
for i in C:
    if i not in D:
        D.append(i)
        
for i in D:
    if i in B:
        B.remove(i)

print(len(B))