#include <bits/stdc++.h>
//#include <chrono>
//#pragma GCC optimize("Ofast")
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<60);

template<class T> bool chmin(T &a, const T &b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T &b){
    if(a < b) {a = b; return true;}
    else return false;
}

int main() {
    cin>>N;
    vec a(N);
    mat dp(N + 1, vec(10, -INF));
    dp[0][0] = 0;
    rep(i, N){
        cin>>a[i];
        a[i] %= 10;
        rep(j, 10){
            chmax(dp[i + 1][j], dp[i][j]);
            chmax(dp[i + 1][(j + a[i]) % 10], dp[i][j] + 1);
        }
    }
    cout<<dp[N][0]<<endl;
}