#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define fs first
#define se second
#define pi 2*acos(0)
#define PI 3.14159265358979323846264338

typedef long long ll;
typedef pair < int , int > pii;
typedef pair < ll , ll > pll;
const int N = 100010;

inline int in() {int x; scanf("%d",&x); return x;}
inline ll lin() {ll x; scanf("%lld",&x); return x;}

int fx[]={1,-1,0,0};
int fy[]={0,0,-1,1};

int n;
int inp[105];

int main(){
    n = in();
    for(int i = 1;i <= n; i++){
        inp[i] = in();
    }

    sort(inp + 1, inp + n + 1);

    int ans = 0;
    for(int i = 1;i <= n; i++){
        int cnt = 1;
        for(int j = i + 1; j <= n; j++){
            int x = abs(inp[i] - inp[j]);
            if(x <= 1) cnt++;
            else break;
        }

        ans = max(ans,cnt);
    }

    printf("%d\n",ans);
}