#include <bits/stdc++.h>
#define be(v) (v).begin(),(v).end()
#define pb(q) push_back(q)
typedef long long ll;
using namespace std;
const ll mod=1000000007, INF=(1LL<<60);
#define doublecout(a) cout<<fixed<<setprecision(10)<<a<<endl;

int main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);
    ll n;
    cin >> n;
    vector<ll> a(n);
    vector<vector<ll> > b(n + 1, vector<ll> (10, -INF));
    for(int i=0;i<n;i++){
        cin >> a[i];
        a[i] %= 10;
    }
    b[0][0] = 0;
    for(int i=0;i<n;i++){
        for(int j=0;j<10;j++) b[i+1][j] = b[i][j];
        for(int j=0;j<10;j++){
            b[i+1][(j + a[i]) % 10] = max(b[i+1][(j + a[i]) % 10], b[i][j] + 1);
        }
    }
    cout << b[n][0] << endl;

    return 0;
}