#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void read(T &x) {
  x = 0;
  register char c = getchar();
  bool f = 0;
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  if (c == '-') c = getchar(), f = 1;
  while (c >= '0' && c <= '9') x = x * 10 + c - 48, c = getchar();
  x = f ? -x : x;
  return;
}
template <class T>
inline void write(T x) {
  if (!x) {
    putchar(48);
    return;
  }
  if (x < 0) x = -x, putchar('-');
  int len = -1, z[20];
  while (x > 0) z[++len] = x % 10, x /= 10;
  for (register int i = len; i >= 0; i--) putchar(z[i] + 48);
  return;
}
const int N = 5010, M = 100010;
int f[N][N], a[N];
int pre[M], mod[10];
int main() {
  int n, ans = 0;
  read(n);
  for (int i = 1; i <= n; i++) read(a[i]);
  for (int i = 0; i <= n; i++) {
    memset(mod, 0, sizeof(mod));
    memset(pre, 0, sizeof(pre));
    for (int j = 1; j < i; j++) {
      pre[a[j]] = max(pre[a[j]], f[i][j]);
      mod[a[j] % 7] = max(mod[a[j] % 7], f[i][j]);
    }
    for (int j = i + 1; j <= n; j++) {
      f[i][j] = max(pre[a[j] - 1], pre[a[j] + 1]) + 1;
      f[i][j] = max(f[i][j], f[i][0] + 1);
      f[i][j] = max(f[i][j], mod[a[j] % 7] + 1);
      f[j][i] = f[i][j];
      pre[a[j]] = max(pre[a[j]], f[i][j]);
      mod[a[j] % 7] = max(mod[a[j] % 7], f[i][j]);
      ans = max(ans, f[i][j]);
    }
  }
  printf("%d\n", ans);
  return 0;
}
