#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
#include <cctype>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <utility>
#include <fstream>

using namespace std;
typedef long long ll;
using ull = unsigned long long;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a, T b) { a = abs(a), b = abs(b); while (b > 0) { tie(a, b) = make_pair(b, a % b); } return a; }
//mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
//constexpr long long mod = 1000000007LL;
constexpr long long mod = 998244353;
constexpr int MAX = 1100000;

int main()
{

	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int n; cin >> n;
	vector<ll> a(n); for (int i = 0; i < n; i++) cin >> a[i];
	sort(a.begin(), a.end());
	map<ll, ll> dp;
	for (int i = 0; i + 1 < n; i++) if (a[i] + 1 == a[i + 1]) dp[a[i] + 2] += 1;
	ll res = n;
	while (dp.size()) {
		ll f1 = dp.begin()->first;
		ll f2 = dp.begin()->second;
		dp.erase(dp.begin());
		res += f2;
		if (binary_search(a.begin(), a.end(), f1 + 1)) {
			dp[f1 + 2] += f2;
		}
	}
	cout << res << endl;
}