#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <deque>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <cassert>
#include <iostream>
#include <stdio.h>
#include <time.h>
 
using namespace std;

typedef long long ll;
 
#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
 
#define MOD 1000000007

ll dp[200010][10];

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