#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

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

    int n;
    cin >> n;

    vector<int> dp(10, -1e9);
    dp[0] = 0;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;
        a %= 10;

        vector<int> ndp(10, 0);
        for (int j = 0; j < 10; j++) {
            ndp[(j + a) % 10] = max(dp[(j + a) % 10], dp[j] + 1);
        }
        dp = move(ndp);
    }
    cout << dp[0] << newl;
    return 0;
}