#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

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

  vector<int> dp(10, -1);
  dp[0] = 0;

  REP (i, n) {
    vector<int> dq = dp;
    REP (j, 10) {
      if (dp[j] != -1) {
        int k = (j + a[i]) % 10;
        dq[k] = max(dp[k], dp[j] + 1);
      }
    }
    dp = dq;
  }

  cout << dp[0] << endl;
  
  return 0;
}