#include <bits/stdc++.h>   #pragma GCC optimize( Ofast,unroll-loops,no-stack-protector )   using namespace std;   mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());   const int N = 3005;   map<int, vector<int> > dif;   vector<int> mod[8];   int a[N];   int n;   template <class C, class F>   struct Mcmf {     static constexpr F eps = (F)1e-9;     struct Edge {       int u, v, inv;       F cap, flow;       C cost;       Edge(int u, int v, C cost, F cap, int inv)           : u(u), v(v), cost(cost), cap(cap), flow(0), inv(inv) {}     };     int second, t, tm, n, m = 0;     vector<vector<Edge> > g;     vector<Edge*> prev;     vector<C> cost;     vector<int> state;     Mcmf(int n, int ss = -1, int tt = -1)         : n(n), g(n + 5), cost(n + 5), state(n + 5), prev(n + 5) {       second = n + 1;       tm = n + 2;       t = n + 3;     }     void add(int u, int v, C cost, F cap) {       g[u].push_back(Edge(u, v, cost, cap, int(g[v].size())));       g[v].push_back(Edge(v, u, -cost, 0, int(g[u].size()) - 1));       m += 2;     }     bool bfs() {       fill(begin(state), end(state), 2);       fill(begin(cost), end(cost), numeric_limits<C>::max());       fill(begin(prev), end(prev), nullptr);       deque<int> qu;       qu.push_back(second);       state[second] = 1, cost[second] = 0;       while (int(qu.size())) {         int u = qu.front();         qu.pop_front();         state[u] = 0;         for (Edge& e : g[u])           if (e.cap - e.flow > eps)             if (cost[u] + e.cost < cost[e.v]) {               cost[e.v] = cost[u] + e.cost;               prev[e.v] = &e;               if (state[e.v] == 0 ||                   (int(qu.size()) && cost[qu.front()] > cost[e.v]))                 qu.push_front(e.v);               else if (state[e.v] == 2)                 qu.push_back(e.v);               state[e.v] = 1;             }       }       return cost[t] != numeric_limits<C>::max();     }     pair<C, F> minCostFlow() {       C cost = 0;       F flow = 0;       while (bfs()) {         F nflow = numeric_limits<F>::max();         for (Edge* e = prev[t]; e != nullptr; e = prev[e->u])           nflow = min(nflow, e->cap - e->flow);         for (Edge* e = prev[t]; e != nullptr; e = prev[e->u]) {           e->flow += nflow;           g[e->v][e->inv].flow -= nflow;           cost += e->cost * nflow;         }         flow += nflow;       }       return make_pair(cost, flow);     }   };   int main() {     cin.tie(0)->sync_with_stdio(0), cout.tie(0);     cin >> n;     for (auto i = (0) - ((0) > (n)); i != n - ((0) > (n));          i += 1 - 2 * ((0) > (n)))       cin >> a[i];     Mcmf<int, int> mcmf(2 * n);     for (auto i = (0) - ((0) > (n)); i != n - ((0) > (n));          i += 1 - 2 * ((0) > (n))) {       mcmf.add(mcmf.second, (i), 0, 1);       mcmf.add((i), (n + (i)), -1, 1);       mcmf.add((n + (i)), mcmf.tm, 0, 1);       for (auto j = (i + 1) - ((i + 1) > (n)); j != n - ((i + 1) > (n));            j += 1 - 2 * ((i + 1) > (n)))         if (a[i] % 7 == a[j] % 7 || abs(a[i] - a[j]) <= 1)           mcmf.add((n + (i)), (j), 0, 1);     }     mcmf.add(mcmf.tm, mcmf.t, 0, 4);     auto best = mcmf.minCostFlow();     ;     cout << -best.first <<   n ;     return 0;   }   