#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(int argc, const char * argv[]) {
    
    int n;
    cin >> n;
    
    vector<int> v(n);
    for (int i=0; i<n; ++i) {
        cin >> v[i];
    }
    
    sort(v.begin(), v.end());
    
    int max_ = 0;
    for (int i=0; i<n; ++i) {
        for (int j=i+1; j<n; ++j) {
            if (v[j] - v[i] > 1) {
                break;
            }
            
            max_ = max(max_, 1+j-i);
        }
    }

    cout << max_ << endl;
    return 0;
}