#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <string>
#include <map>
#include <math.h>
#include <cmath>
#include <climits>
#include <unordered_map>
#include <unordered_set>
#include <assert.h>
#include <fstream>
#include <bitset>
#include <iomanip>
typedef long long ll;
using namespace std;
int MOD = (int)1e9;
int MAXN = 1e6;
//classes
//global
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
//ifstream fin("input.txt");
//ofstream fout("output.txt");
//stop
int n;
cin >> n;
vector<int> vec(n);
for(int& i: vec) cin >> i;
vector<bool> valid(n, true);
vector<int> parent(n, -1);
for(int i = 1; i < n; i++){
int index = -1;
for(int j = 0; j < i; j++){
if(vec[i] == vec[j]-1 && valid[j]){
index = j;
}
}
//cout << "i: " << i << " index: " << index << '\n';
if(index > -1){
valid[index] =false;
parent[i] = index;
}
}
int sum = 0;
for(bool i: valid) if(i) sum++;
cout << sum << '\n';
return 0;
}
