#include <bits/stdc++.h>
using namespace std;
/* typedef */
typedef long long ll;
typedef pair<int, int> pii;
/* constant */
const int INF = 1 << 30;
const ll LINF = 1LL << 61;
const int NIL = -1;
const int MAX = 10000;
const int MOD = 1000000007;
const double pi = 3.141592653589;
/* global variables */
/* function */
/* main */
int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    for (int &ai : a) cin >> ai;

    vector<int> dp(10, NIL);  // mod 10
    dp[0] = 0;
    for (int i = 0; i < n; i++) {
        vector<int> tmp = dp;
        for (int k = 0; k < 10; k++) {
            if (dp[k] == NIL) continue;
            int nk = (a[i] + k) % 10;
            tmp[nk] = max(tmp[nk], dp[k] + 1);
        }
        swap(tmp, dp);
    }
    cout << dp[0] << '\n';
}