#include <bits/stdc++.h>
using namespace std;
const int N = 3e3 + 5;
const int INF = 1e9;
struct Edge {
  int from, to;
  int capacity, cost;
  Edge(int from, int to, int cap, int cost)
      : from(from), to(to), capacity(cap), cost(cost) {}
};
vector<vector<int>> adj;
vector<vector<int>> cost, capacity;
void shortest_paths(int n, int v0, vector<int>& d, vector<int>& p) {
  d.assign(n, INF);
  d[v0] = 0;
  vector<bool> inq(n, false);
  queue<int> q;
  q.emplace(v0);
  p.assign(n, -1);
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    inq[u] = false;
    for (int v : adj[u]) {
      if (capacity[u][v] > 0 && d[v] > d[u] + cost[u][v]) {
        d[v] = d[u] + cost[u][v];
        p[v] = u;
        if (!inq[v]) {
          inq[v] = true;
          q.emplace(v);
        }
      }
    }
  }
}
int min_cost_flow(int N, const vector<Edge>& edges, int K, int s, int t) {
  adj.assign(N, vector<int>());
  cost.assign(N, vector<int>(N, 0));
  capacity.assign(N, vector<int>(N, 0));
  for (Edge e : edges) {
    adj[e.from].emplace_back(e.to);
    adj[e.to].emplace_back(e.from);
    cost[e.from][e.to] = e.cost;
    cost[e.to][e.from] = -e.cost;
    capacity[e.from][e.to] = e.capacity;
  }
  int flow = 0;
  int cost = 0;
  vector<int> d;
  vector<int> p;
  while (flow < K) {
    shortest_paths(N, s, d, p);
    if (d[t] == INF) break;
    int f = K - flow;
    int cur = t;
    while (cur != s) {
      f = min(f, capacity[p[cur]][cur]);
      cur = p[cur];
    }
    flow += f;
    cost += f * d[t];
    cur = t;
    while (cur != s) {
      capacity[p[cur]][cur] -= f;
      capacity[cur][p[cur]] += f;
      cur = p[cur];
    }
  }
  return cost;
}
int n;
int a[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  vector<Edge> edges;
  int nodes = 2 * n + 3;
  int source = nodes - 2, sink = nodes - 1;
  edges.emplace_back(source, 0, 4, 0);
  for (int i = 1; i <= n; i++) {
    edges.emplace_back(0, i, 1, 0);
    edges.emplace_back(i, i + n, 1, -1);
    edges.emplace_back(i + n, sink, 1, 0);
    int c1 = 3, c2 = 3, c3 = 3;
    for (int j = i + 1; j <= n; j++) {
      if (a[i] - a[j] == 1 && c1) {
        edges.emplace_back(i + n, j, 1, 0);
        c1--;
      } else if (a[i] - a[j] == -1 && c2) {
        edges.emplace_back(i + n, j, 1, 0);
        c2--;
      } else if (a[i] % 7 == a[j] % 7 && c3) {
        edges.emplace_back(i + n, j, 1, 0);
        c3--;
      }
    }
  }
  cout << -min_cost_flow(nodes, edges, INF, source, sink) << '\n';
  return 0;
}
