#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tlll tuple<ll,ll,ll>
const ll mxn = 1e6+10;
int N;
map<int,int> mp;
int arr[mxn];
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>N;
for(int i = 1;i<=N;i++)cin>>arr[i];
for(int i = 1;i<=N;i++){
if(mp.find(arr[i]) != mp.end()){
mp[arr[i]]--;
if(!mp[arr[i]])mp.erase(arr[i]);
}
mp[arr[i]-1]++;
}
ll ans = 0;
for(auto &i:mp)ans += i.sc;
cout<<ans<<'\n';
}
