#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N;
  cin >> N;
  vector<int> A(N);
  for (auto&& e : A) {
    cin >> e;
    e %= 10;
  }
  vector<int> dp(10, -1);
  dp[0] = 0;
  for (int i = 0; i < N; i++) {
    vector<int> ndp(10, -1);
    for (int j = 0; j < 10; j++) {
      if (dp[j] == -1) continue;
      ndp[j] = max(ndp[j], dp[j]);
      ndp[(j + A[i]) % 10] = max(ndp[(j + A[i]) % 10], dp[j] + 1);
    }
    dp = ndp;
  }
  cout << dp.front() << '\n';
  return 0;
}