#include <bits/stdc++.h>

#define pp pop_back
#define pb push_back
#ifdef KTL
  #define fname ""
#else
  #define fname "travel."
#endif
#define forn(i, x, n) for (int i = int(x); i <= int(n); ++i)
#define for1(i, n, x) for (int i = int(n); i >= int(x); --i)
#define mp make_pair
#define s second
#define f first
#define sz(a) (int)((a).size())

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pi;

const int N = 5e5;
const int mod = 1e9 + 7;

int n, a[N];

int main() {
  #ifdef wws
    freopen("in", "r", stdin);
  #endif
  ios_base :: sync_with_stdio(NULL), cin.tie(NULL), cout.tie(NULL);
  cin >> n;
  for (int i = 1;i <= n;i++)
  {
    cin >> a[i];
  }
  int ans = 0;
  for (int mn = 1;mn < 100;mn++)
  {
    int now = 0;
    for (int i = 1;i <= n;i++) if (a[i] == mn || a[i] == mn + 1) now++;
    ans = max(ans, now);
  }
  cout << ans << endl;
  return 0;
}