#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#define fast_io ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)



int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n;
    cin >> n;
    int x;
    int d[100]={0};
    while(n--) cin >> x, d[x]++;
    int m=0,index=-1;
    for(int i=1;i<99;i++) {
        if(m<d[i]+d[i+1]){
            m = d[i]+d[i+1];
            index = i;
        }
    }
    cout << d[index] + d[index+1] << endl;
    return 0;
}