#include <bits/stdc++.h>
        #define s(a) cin >> a;
        #define s2(a,b) cin >> a>> b;
        #define s3(a,b,c) cin >> a>> b>> c;
        #define s4(a,b,c,d) cin >> a>> b >> c >> d;
        #define sp(b) cout << b << "\n";
        #define sp2(b,c) cout << b << " "<<c <<endl; 
        #define sp3(a,b,c) cout <<a <<" "<< b << " "<<c <<endl; 
        #define p(a) ////printf("%lld\n",a);
        #define p2(a,b) ////printf("%lld %lld",a,b);
        #define pm(a) ////printf("a\n");
        #define test(t) while(t>0)
        #define sl(a) a.length()
        #define f(a,b,c) for(int a=b;a<c;a++)
        #define v(a,b) vector<a> b;
        #define pb(a,b) a.push_back(b);
        #define ll long long
        #define mem(a,b) memset(a,b,sizeof(a));
        #define fillar(ar,n) f(i,0,n) s(ar[i]);
        #define diff(a,b) abs(a-b);
        using namespace std;
        #define MOD 1000000007



int main(){
        int i,j,k;
      int n;
      s(n);
      int ar[n];
      f(i,0,n){
        s(ar[i]);
      }
      sort(ar,ar+n);
      int maxx=0;
      f(i,0,n){
          j=i+1;
          while(abs(ar[j]-ar[i])<=1 && j<n){
                  j++;
              }
          maxx=max(maxx,j-i);
      }
      printf("%d\n",maxx );
    return 0;

    }