#include <bits/stdc++.h>
using namespace std;
int main(){
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int n;
    cin>>n;
    int arr[100];
    memset(arr,0,sizeof(arr));
    for(int i=0;i<n;i++){
        int p;
        cin>>p;
        if(p!=100)
            arr[p]++;
        if(p!=0)
            arr[p-1]++;
    }
    sort(arr,arr+100);
    cout<<arr[99]<<endl;
    return 0;
}