#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
ll dp[int(1e5) * 2 + 5][10];

int main() {
    ll N;
    cin >> N;
    vector<ll> a(N);
    rep(i, N) {
        cin >> a[i];
    }
    rep(i, N + 1) rep(j, 10) {
        dp[i][j] = -1;
    }
    dp[0][0] = 0;
    rep(i, N) rep(j, 10) {
        if (dp[i][j] == -1) {
            continue;
        }
        dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
        dp[i + 1][(j + a[i]) % 10] = max(dp[i + 1][(j + a[i]) % 10], dp[i][j] + 1);
    }
    cout << dp[N][0] << endl;

    return 0;
}