#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<int(n); ++i)
#define repll(i,m,n) for(ll i=m; i<ll(n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fi first
#define se second

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

template<typename T> T gcd(T a, T b){ return a % b ? gcd(b, a % b) : b; }
template<typename T> T lcm(T a, T b){ return a / gcd(a, b) * b; }

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    cin >> N;
    vector<int> A(N);
    rep(i, 0, N){
        cin >> A[i];
        A[i] %= 10;
    }

    vector dp(N+1, vector<int>(10, -1));
    dp[0][0] = 0;

    rep(i, 0, N){
        rep(j, 0, 10){
            if(dp[i][j] == -1) continue;
            chmax(dp[i+1][(j + A[i]) % 10], dp[i][j] + 1);
            chmax(dp[i+1][j], dp[i][j]);
        }
    }
    cout << dp[N][0] << endl;

    return 0;
}