#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cmath>
#include <climits>
#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <cassert>
#include <vector>
#define all(x) x.begin() , x.end()
#define fi first
#define se second
#define pb push_back
#define umax( x , y ) x = max( x , (y) )
#define umin( x , y ) x = min( x , (y) )
#define For( i , a ) for(int i=1;i<=a;i++)
#define ort (b+s)/2
#define y2 asrwjaelkf
#define y1 asseopirwjaelkf
#define set multiset

using namespace std;

inline int read() {
    int res = 0 ;int neg ;
    while(true){char ch = getchar();if(ch>='0' && ch<='9' || ch=='-'){if(ch=='-') neg = -1;else neg = 1 , res = ch-'0';break;} }
    while(true){char ch = getchar();if(ch>='0' && ch<='9') res*=10 , res+=ch-'0';else break;}
    return res*neg;
}


typedef long long Lint;
typedef double db;
typedef pair<int,int> ii;
typedef pair<db,db> dd;
typedef pair<db,int> di;
typedef pair<ii,int> iii;
typedef pair<ii,ii> i4;

const int maxn = 100020;
const int maxm = 1000020;
const int MOd = 1e9 + 7;

int dn[maxn][40], dn2[maxn];
int ar[maxn], a;

int main() {

    //freopen("asd.in.c","r",stdin);
    //freopen("out.txt","w",stdout);

    scanf("%d",&a);
    for(int i=1;i<=a;i++) scanf("%d",&ar[i]);
    sort( ar+1, ar+1+a );
    int ans = 0;
    for(int i=1,j=1;i<=a;i++) {
        while( j < i && ar[j] < ar[i] - 1 ) j++;
        umax( ans, i-j+1 );
    }
    cout << ans << endl;
    return 0;
    dn[2][1] = 1;
    for(int i=2;i<=a;i++) {

        for(int j=1;j<i;j++)
            dn[i+1][j] += j * dn[i][j], dn[i+1][j+1] = (i-j) * dn[i][j];
        int ans = 0;
        for(int j=1;j<i;j++) printf("%d ",dn[i][j]), ans += dn[i][j] * j; printf("---- %d\n",ans*i);
    }
    return 0;
}