#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
#define DUMP(x) cout << #x << " = " << (x) << endl;
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define IFOR(i, m, n) for (ll i = n - 1; i >= m; i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
#define FOREACH(x, a) for (auto&(x) : (a))
#define ALL(v) (v).begin(), (v).end()
#define SZ(x) ll(x.size())

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

int main() {
  ll n;
  cin >> n;
  vector<ll> a(n);
  REP(i, n) { cin >> a[i]; }
  vector<vector<ll>> dp(n + 1, vector<ll>(10, -1));
  dp[0][0] = 0;
  REP(i, n) REP(j, 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;
}