#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  int A[N];
  for(int i=0;i<N;i++){
    cin >> A[i];
    A[i]%=10;
  }
  int dp[N+5][15];
  for(int i=0;i<=N;i++){
    for(int j=0;j<=9;j++){
      dp[i][j] = -10000000;
    }
  }
  dp[0][0] = 0;
  for(int i=0;i<N;i++){
    for(int j=0;j<=9;j++){
      dp[i+1][j] = max(dp[i+1][j], dp[i][(10+j-A[i])%10]+1);
      dp[i+1][j] = max(dp[i+1][j], dp[i][j]);
    }
  }
  cout << dp[N][0] << endl;
  return 0;
}