#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
    int N;
    cin >> N;
    int A[N];
    for (int i = 0; i < N; i++) {
        cin >> A[i];
        A[i] %= 10;
    }
    ll dp[N + 1][10];
    for (int i = 0; i <= N; i++) {
        for (int j = 0; j < 10; j++) {
            dp[i][j] = -1;
        }
    }
    dp[0][0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < 10; j++) {
            dp[i + 1][j] = dp[i][j];
        }
        for (int j = 0; j < N; j++) {
            if (dp[i][j] == -1) continue;
            int t = (j + A[i]) % 10;
            dp[i + 1][t] = max(dp[i + 1][t], dp[i][j] + 1);
        }
    }
    cout << dp[N][0] << "\n";
    return 0;
}