#include <bits/stdc++.h>
using namespace std;
#define INF 1000000000
#define MOD 1000000007
#define FOR(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define REP(i, b) FOR(i, 0, b)
#define ALL(x) (x).begin(),(x).end()
typedef long long ll;
#define endl '\n'
int dp[200001][10];

int main() {
  int n;
  vector<int> a;
  cin >> n;
  a.resize(n);
  REP(i, n) {
    cin >> a[i];
    REP(j, 10) {
      dp[i][j] = -1;
    }
  }
  dp[0][0] = 0;
  dp[0][a[0] % 10] = 1;
  FOR(i, 1, n) {
    REP(j, 10) {
      if(dp[i - 1][(10 + j - a[i] % 10) % 10] >= 0) {
        dp[i][j] = dp[i - 1][(10 + j - a[i] % 10) % 10] + 1;
      }
      dp[i][j] = max(dp[i - 1][j], dp[i][j]);
    }
  }
  cout << dp[n - 1][0] << endl;
  return 0;
}