#include <bits/stdc++.h>
using namespace std;
template <class T>
void dbs(string str, T t) {
  cerr << str << " : " << t << "\n";
}
template <class T, class... S>
void dbs(string str, T t, S... s) {
  int idx = str.find(',');
  cerr << str.substr(0, idx) << " : " << t << ",";
  dbs(str.substr(idx + 1), s...);
}
template <class S, class T>
ostream& operator<<(ostream& os, const pair<S, T>& p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class S, class T>
ostream& operator<<(ostream& os, const map<S, T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class T>
void prc(T a, T b) {
  cerr << "[";
  for (T i = a; i != b; ++i) {
    if (i != a) cerr << ", ";
    cerr << *i;
  }
  cerr << "]\n";
}
const int N = 5000;
int dp[N + 1][N + 1];
int a[N + 1];
int dp1[100010];
int mod1[7];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  int n;
  cin >> n;
  for (int i = (int)(1); i <= (int)(n); i++) {
    int temp;
    cin >> temp;
    a[i] = temp;
  }
  int answer1 = 0;
  for (int i = (int)(0); i <= (int)(n); i++) {
    for (int i = (int)(0); i <= (int)(n); i++) dp1[a[i]] = 0;
    for (int i = (int)(0); i <= (int)(6); i++) mod1[i] = 0;
    for (int j = (int)(0); j <= (int)(n); j++) {
      if (i == j and j == 0) continue;
      if (i == j) continue;
      if (i < j) {
        answer1 = max(answer1, dp[i][j] = dp[j][i] =
                                   1 + max({dp[i][0], mod1[a[j] % 7],
                                            dp1[a[j] - 1], dp1[a[j] + 1]}));
      }
      mod1[a[j] % 7] = max(mod1[a[j] % 7], dp[i][j]);
      dp1[a[j]] = max(dp1[a[j]], dp[i][j]);
    }
  }
  cout << answer1 << "\n";
  return 0;
}
