#include <bits/stdc++.h>
using namespace std;
#define forsn(i, s, n) for(int i=s;i<int(n);i++)
#define forn(i, n) forsn(i, 0, n)
#define all(v) v.begin(), v.end()
#define NACHO ios_base::sync_with_stdio(0);cin.tie(NULL);
typedef long long tint;
int main(){
int n; cin >> n;
vector<int> a (n);
forn(i, n) cin >> a[i];
vector<int> visited (1000002, 0);
vector<bool> tiene (n, 0);
forn(i, n){
visited[a[i]]++;
if(visited[a[i]+1]){ tiene[i] = 1; visited[a[i]+1]--;}
}
int cont = 0;
forn(i, n){
if(tiene[i] == 0) cont++;
}
cout << cont << "\n";
}
