#include <iostream>  
#include <algorithm>  
#include <vector>  
using namespace std;
int main() 
{
    int n,maxl = 0,l=1;
    cin >> n;
    vector<long long> a(n);
    for (int i = 0; i < n; i++)
    { 
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    for (int i = 0; i < n - 1; i++) 
    {
        if (a[i + 1] == a[i] + 1) 
        {
            l++; 
        }
        else {
            maxl = max(maxl, l); 
            l = 1; 
        }
    }
    maxl = max(maxl, l);
    cout << maxl << endl;
    return 0;
}

求解！谢谢佬！