#include <algorithm>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;

#define MOD 1000000007

int main() {
  int n;
  cin >> n;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
  }
  vector<vector<ll> > dp(n + 1, vector<ll>(10, -1));
  dp[0][0] = 0;
  for (int i = 1; i <= n; ++i) {
    for (int j = 0; j <= 9; ++j) {
      dp[i][j] = max(dp[i][j], dp[i - 1][j]);
      if (dp[i - 1][j] != -1) {
        dp[i][(j + a[i]) % 10] = max(dp[i][(j + a[i]) % 10], dp[i - 1][j] + 1);
      }
    }
  }
  cout << dp[n][0] << endl;
  return 0;
}