#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int dp[200020][10] = { 0 };
int a[200020];
int main() {
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		a[i] %= 10;
	}
	dp[0][0] = 1;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j < 10; j++) {
			if (dp[i - 1][j] != 0) {
				dp[i][j] = dp[i - 1][j];
				dp[i][(j + a[i]) % 10] = max(dp[i][(j + a[i]) % 10], dp[i - 1][j] + 1);
			}
		}
	}
	cout << dp[n][0] - 1 << endl;
}