// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h> 
using namespace std;
typedef long long ll;
#define endl '\n'
#define all(x) (x).begin(),(x).end()
template<typename T1,typename T2> bool chmin(T1 &a,T2 b){if(a<=b)return 0; a=b; return 1;}
template<typename T1,typename T2> bool chmax(T1 &a,T2 b){if(a>=b)return 0; a=b; return 1;}
int dx[4]={0,1,0,-1}, dy[4]={1,0,-1,0};
long double eps = 1e-9;
long double pi = acos(-1);




signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);

    ll n;
    cin>>n;
    ll a[n];
    map<ll,ll> mp;
    for(int i=0;i<n;i++){
        cin>>a[i];
        mp[a[i]] = 1;
    }
    sort(a,a+n);
    ll ans = n;
    auto itr = mp.end();
    while(itr != mp.begin()){
        itr--;
        ll nx = itr->first + 2;
        if(mp.count(nx)){
            mp[nx-2] += mp[nx];
        }
    }
    for(int i=1;i<n;i++){
        if(a[i]-1 == a[i-1]){
            ans += mp[a[i]]-1;
        }
    }
    ll cnt = 1;
    for(int i=1;i<n;i++){
        if(a[i]-1 == a[i-1])cnt++;
        else {
            ans += cnt - 1;
            cnt = 1;
        }
    }
    ans += cnt - 1;
    cout << ans << endl;
    
}