#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ul = unsigned long;
using ull = unsigned long long;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n;
	cin >> n;

	vector<int> a(n + 1, 0);

	for (int i = 1; i <= n; ++i)
	{
		cin >> a[i];
		a[i] %= 10;
	}

	vector<int> dp(10, -1e9);
	dp[0] = 0;

	for (int i = 1; i <= n; ++i)
	{
		vector<int> dpw(10, 0);
		for (int j = 0; j < 10; ++j)
		{
			int mod = (j + a[i]) % 10;
			dpw[mod] = max(dp[j] + 1, dp[mod]);
		}

		for (int i = 0; i < 10; ++i)
			dp[i] = dpw[i];
	}

	cout << dp[0] << "\n";

	return 0;
}