#include <algorithm>
#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <map>
#define rep(i,n) for (int i=0; i<n; ++i)
#define FOR(i,a,b) for (int i=a; i<b+1; ++i)
#define pb(x) push_back(x)
#define ll long long
using namespace std;

int main () {
  int n;
  cin  >> n;
  int x[n];
  rep(i,n) cin >> x[i];
  sort(x, x + n);
  int serials = 1, cnt = n;
  FOR(i,1,n - 1) {
    if (x[i - 1] +1== x[i]) {
        serials++;
    } else {
       cnt -= serials - serials % 2;
       serials = 1;
    }
  }
  cout << cnt << endl;
  return 0;
}