#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

bool check(vector<int> &a, int m) {
  for (int i = 0; i < a.size(); i++) {
    int j = i - m;
    if (j < 0) continue;
    if (a[i] - a[j] < 2)
      return false;
  }
  return true;
}

int solve(vector<int> &a) {
  int n = a.size();

  sort(a.begin(), a.end());

  int lo = 0;
  int hi = n;

  while (hi - lo > 1) {
    int mi = (lo + hi) / 2;
    if (check(a, mi))
      hi = mi;
    else
      lo = mi;
  }
  return hi;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  vector<int> a(n);
  REP (i, n) cin >> a[i];

  cout << solve(a) << endl;
  
  return 0;
}