#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <cassert>
#include <unordered_map>

using namespace std;

int n;
int a[105];

int main(){
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf("%d", a + i);
    }
    sort(a, a + n);
    int ans = 1;
    int maxans = 1;
    int num = a[0];
    for (int i = 1; i < n; i++) {
        if (abs(a[i] - num) <= 1) ans++;
        else {
            maxans = max(ans, maxans);
            ans = 1;
            num = a[i];
        }
    }
    maxans = max(ans, maxans);
    //assert(maxans >= 2);
    printf("%d\n", maxans);
    return 0;
}