n = int(input())
alst = list(map(int, input().split()))
ans = 0
cnt = [0 for _ in range(10)]
for a in alst:
    cnt[a % 10] += 1
for i in range(10):
    if i == 0:
        ans += cnt[i]
        cnt[i] = 0
    elif i % 2 == 0:
        ans += cnt[i] // 5
        cnt[i] %= 5
    elif i == 5:
        ans += cnt[i] // 2
        cnt[i] %= 2
    else:
        ans += cnt[i] // 10
        cnt[i] %= 10

sub = 0
def solve(num = 1, n = 0, total = 0):
    global sub
    if num == 10:
        if total % 10 == 0:
            sub = max(n, sub)
        return
    for i in range(cnt[num] + 1):
        solve(num + 1, n + i, total + i * num)
    
solve()
print(ans + sub)