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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int dp[200020][10];

void chmax(int& a, int b) {
  if (a < b) a = b;
}

int main() {
  int n;
  cin >> n;

  vector<int> a(n);
  rep(i, n) {
    cin >> a[i];
    a[i] %= 10;
  }

rep(i, n) {
  rep(j, 10) {
    dp[i][j] = -1;
  }
}

dp[0][0] = 0;
  rep(i, n) {
    rep(j, 10) {
      if (dp[i][j] == -1) continue;
      chmax(dp[i+1][(j + a[i]) % 10], dp[i][j] + 1);
      chmax(dp[i+1][j], dp[i][j]);
    }

  }


  cout << dp[n][0] << endl;


  

}