/**
 *   @FileName	b.cpp
 *   @Author	kanpurin
 *   @Created	2020.09.18 21:52:23
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;cin >> n;
    constexpr int INF = 1e9 + 6;
    vector<vector<int>> dp(n+1,vector<int>(10,-INF));
    dp[0][0] = 0;
    for (int i = 0; i < n; i++) {
        int a;cin >> a;
        for (int j = 0; j < 10; j++) {
            dp[i + 1][(j + a) % 10] = dp[i][(j + a) % 10];
            if (dp[i][j] == -INF) continue;
            dp[i + 1][(j + a) % 10] = max(dp[i + 1][(j + a) % 10],dp[i][j] + 1);
        }
    }
    cout << dp[n][0] << endl;
    return 0;
}