#include <bits/stdc++.h>
#define be(v) (v).begin(),(v).end()
#define pb(q) push_back(q)
typedef long long ll;
using namespace std;
const ll mod=1000000007, INF=(1LL<<60);
#define doublecout(a) cout<<fixed<<setprecision(10)<<a<<endl;

int main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);
    ll n;
    cin >> n;
    ll a[n];
    set<ll> s;
    for(int i=0;i<n;i++){
    	cin >> a[i];
    	s.insert(a[i]);
    }
    sort(a, a+n);
    ll ans = 0;
    map<ll, ll> mp;
    for(int i=0;i<n;i++){
    	mp[a[i]]++;
    	mp[a[i] + 1] += mp[a[i] - 1]; 
    }
    for(auto& i: mp){
    	ans += i.second;
    }
    cout << ans << endl;
    return 0;
}