#include <map>
#include <iostream>
#include<bits/stdc++.h>
using namespace std;
#define test int t;scanf("%d", &t);while(t--)
#define sd(n) scanf("%d", &n)
#define loop(i, n) for(int i = 0;i<n;i++)
#define kloop(i, k, n) for(int i=k;i<n;i++)
#define rloop(i, n) for(int i = n;i>=0;i--)
#define rkloop(i, n, k) for(int i = n;i>=k;i--)
#define MOD 1000000007
#define PI 3.1415926535897932384626433832795
#define interactive(x) cout<<x<<"\n";fflush(stdout)
#define fil(name, val) memset(name, val, sizeof(name))
#define pb push_back
#define ll long long
/*int fact[MAXN];
int invfact[MAXN];
int inv(int a, int b){
    if(b==0)
        return 1;
    if(b&1)
        return (long long)a*inv(a, b-1)%MOD;
    else{
        int res = inv(a, b>>1);
        return (long long)res*res%MOD;
    }
}
void init(){
    fact[0] = 1;
    for(int i=1;i<MAXN;i++){
        fact[i] = (long long)fact[i-1]*i%MOD;
    }
    invfact[MAXN-1] = inv(fact[MAXN-1], MOD-2);
    for(int i=MAXN-1;i>0;i--){
        invfact[i-1] = (long long)invfact[i]*i%MOD;
    }
}
int C(int n, int r){
    if(r>n || r<0)
        return 0;
    return (long long)((long long)fact[n]*invfact[r]%MOD)*invfact[n-r]%MOD;
}*/
int n, arr[105], mp[105];
void solve(){
    sd(n);
    loop(i, n)  sd(arr[i]);
    int ans = 0;
    fil(mp, 0);
    loop(i, n){
        mp[arr[i]]++;
    }
    loop(i, n){
        int val = arr[i];
        int temp = mp[val];
        if(val-1>0){
            temp+=mp[val-1];
        }
        ans = max(ans, temp);
        temp = mp[val];
        if(val+1<100){
            temp+=mp[val+1];
        }
        ans = max(ans, temp);
    }
    cout<<ans;
}
int main(){
    /*FILE *fin = freopen("C-small-attempt0.in", "r", stdin);
	assert( fin!=NULL );
	FILE *fout = freopen("C-small.out", "w", stdout);*/
    solve();
    return 0;
}