#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>
#include <atcoder/all>
#include <bits/stdc++.h>

#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace atcoder;
using namespace std;
typedef long long int ll;
typedef modint998244353 mint;




ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;

    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}

/*
解説動画参考
解説ブログ参考
https://yukicoder.me/submissions/1030969
*/

int main()
{

   
    int Q;
    Q = 1;
    //cin >> Q;   
    

    
    while (Q--) {
        int n;
        cin >> n;
        vector<int>r(n);
        for (int i = 0; i < n; i++) {
            cin >> r[i];r[i] %= 10;
        }
        vector<vector<ll>>dp(n + 2, vector<ll>(11,-1));
        dp[0][0] = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j <= 10; j++) {
                if (dp[i][j] == -1)continue;
                ll t = (j + r[i]) % 10;
                dp[i + 1][t] = max(dp[i + 1][t], dp[i][j] + 1);
                dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
            }
        }
        cout << dp[n][0];
       
    }

    return 0;
}