G - Picking Numbers

#include <bits/stdc++.h>
using namespace std;

#define int long long
const int N = 1e5 + 5;
const int mod = 1e18 + 7;
const int INF = 1e18;
int dp[N];
int from[N];
int a[N];

signed main()
{
    int n;
    cin >> n;
    map<int , int> cnt;
    for(int i = 0; i < n; i++){
        cin >> a[i];
        cnt[a[i]]++;
    }
    int ans = 1;
    for(int i = 0; i < n; i++){
        ans = max(ans , cnt[a[i]] + cnt[a[i] + 1]);
    }
    cout << ans << endl;
}