#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (!(ch >= '0' && ch <= '9')) {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + (ch - '0');
    ch = getchar();
  }
  return x * f;
}
const int N = 5005;
const int M = 100005;
const int T = 7;
int n, a[N];
int ans = 0;
int dp[N][N];
int mx1[M], mx2[T];
int main() {
  n = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  dp[0][0] = 0;
  for (int j = 0; j <= n; j++) {
    for (int i = 1; i <= j - 1; i++) {
      mx1[a[i]] = max(mx1[a[i]], dp[j][i]);
      mx2[a[i] % 7] = max(mx2[a[i] % 7], dp[j][i]);
    }
    for (int i = j + 1; i <= n; i++) {
      dp[i][j] =
          max(max(mx1[a[i] - 1], mx1[a[i] + 1]), max(dp[j][0], mx2[a[i] % 7])) +
          1;
      mx1[a[i]] = max(mx1[a[i]], dp[i][j]);
      mx2[a[i] % 7] = max(mx2[a[i] % 7], dp[i][j]);
      ans = max(ans, dp[i][j]);
    }
    for (int i = 1; i <= n; i++) mx1[a[i]] = 0;
    for (int i = 0; i <= 6; i++) mx2[i] = 0;
  }
  printf("%d\n", ans);
  return 0;
}
