#include <bits/stdc++.h>
using namespace std;
int INF = 10000000;
int main(){
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
    A[i] %= 10;
  }
  vector<vector<int>> dp(N + 1, vector<int>(10, -INF));
  dp[0][0] = 0;
  for (int i = 0; i < N; i++){
    dp[i + 1] = dp[i];
    for (int j = 0; j < 10; j++){
      dp[i + 1][(j + A[i]) % 10] = max(dp[i + 1][(j + A[i]) % 10], dp[i][j] + 1);
    }
  }
  cout << dp[N][0] << endl;
}