#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main() {
    long long dp[10] = {};
    for (int i = 0; i < 10; i++) dp[i] = -1e18;

    dp[0] = 0;

    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        long long ndp[10];
        memcpy(ndp, dp, sizeof(ndp));
        long long x;
        cin >> x;
        for (int j = 0; j < 10; j++)
            ndp[(j + x) % 10] = max(ndp[(j + x) % 10], dp[j] + 1);
        memcpy(dp, ndp, sizeof(ndp));
    }
    cout << dp[0] << endl;

}