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

rem = [-1] * 10
rem[0] = 0

for i in range(N):
    a = A[i] % 10
    tmp = rem.copy()
    for j in range(10):
        if rem[(j - a) % 10] != -1:
            tmp[j] = max(rem[j], rem[(j - a) % 10] + 1)
    rem = tmp.copy()

print(rem[0])