#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int n;     cin >> n;     int *input = new int[n];     for (int i = 0; i < n; i++) cin >> input[i];     sort(input, input + n);     int over = input[n - 1] + 1;     int ans = 1;     for (int i = n - 2; i >= 0; i--) {       if (input[i] + 1 < over) {         over = input[i] + 1;         ans++;       } else if (input[i] < over) {         over = input[i];         ans++;       } else if (input[i] - 1 > 0 && input[i] - 1 < over) {         over = input[i] - 1;         ans++;       }     }     cout << ans << endl;   }   