#include<bits/stdc++.h>

using namespace std;
using ll = long long;
inline int ri() { int n; cin >> n; return n;}
const int INF = 1e9;

int main()
{
	int n; cin >> n;
	vector<vector<int>> dp(n + 1, vector<int>(10, -INF));
	dp[0][0] = 0;
	for(int i = 0; i < n; i++) {
		int t = ri() % 10;
		for(int j = 0; j < 10; j++) {
			dp[i + 1][(j + t) % 10] = max(dp[i][j] + 1, dp[i + 1][(j + t) % 10]);
			dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
		}
	}
	cout << dp[n][0] << endl;
}