#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define endl "\n";
#define vec vector<ll>
#define vecvec vector<vector<ll>>
using namespace std;
/*#define FileName "connect"
string Ghhhh = ".in";
string Ghhhhh = ".out";
ifstream Girdi(FileName + Ghhhh);
ofstream Cikti(FileName + Ghhhhh);
#define cin Girdi
#define cout Cikti*/
inline void solve(){
ll n;
cin >> n;
map<ll,ll> mapp;
for(ll i = 1 ; i <= n ; i++){
ll x;
cin >> x;
if(mapp[x+1] > 0) mapp[x+1]--;
mapp[x]++;
}
ll ans = 0;
for(auto it : mapp){
if(it.second > 0){
ans += it.second;
}
}
cout << ans << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t = 1;
//cin >> t;
while(t--){
solve();
}
}
