#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx")
// #pragma comment(linker, "/stack:200000000"]

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <bitset>
#include <stack>
#include <random>
#include <fstream>
#include <sstream>
#include <chrono>

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define hm unordered_map
#define pii pair<int, int>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define cinv(v) for (auto& x: v) cin >> x
#define fr(i, n) for (int i = 0; i < n; ++i)
#define fl(i, l, n) for (int i = l; i < n; ++i)

#define int ll

using namespace std;

#ifdef __LOCAL
	#define dbg(x) cerr << #x << " : " << x << '\n'
	const int maxn = 20;
#else
	#define dbg(x)
	const int maxn = 20;
#endif

//tg: @galebickosikasa

ostream& operator << (ostream& out, vector<int>& v) {
	for (auto& x: v) out << x << ' ';
	return out;
}

ostream& operator << (ostream& out, pii& v) {
	out << v.fi << ", " << v.se;
	return out;
}

istream& operator >> (istream& in, pii& a) {
	in >> a.fi >> a.se;
	return in;
}

const ll inf = (ll) 2e9;
const ld pi = asin (1) * 2;
const ld eps = 1e-8;
const ll mod = (ll)1e9 + 7;
const ll ns = 97;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

int mt[maxn], used[maxn], color = 1, odd[maxn];
vector<int> g[maxn];

int dfs (int v) {
	if (used[v] == color) return 0;
	used[v] = color;
	for (auto& u: g[v]) {
		if (mt[u] == -1 || dfs (mt[u])) {
			mt[u] = v;
			return 1;
		}
	}
	return 0;
}

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	for (auto& x: mt) x = -1;
	int n;
	cin >> n;
	vector<int> goo (n);
	cinv (goo);
	map <int, vector<int>> moo;
	fr (i, n) moo[goo[i]].pb (i);
	vector<int> t;
	fr (i, n) {
		int x = goo[i];
		for (auto& u: moo[x - 1]) g[i].pb (u);
		for (auto& u: moo[x + 1]) g[i].pb (u);
		if (x & 1) odd[i] = 1;
	}
	fr (i, n) {
		if (odd[i]) {
			dfs (i);
			++color;
		}
	}
	int ans = 0;
	for (auto& x: used) x = 0;
	fr (i, n) {
		if (odd[i]) continue;
		if (used[i]) continue;
		if (mt[i] != -1) {
			++ans;
			used[i] = used[mt[i]] = 1;
		} else {
			++ans;
			used[i] = 1;
		}
	}
	fr (i, n) {
		if (!used[i]) ++ans;
	}
	cout << ans << '\n';







}