#include <iostream>
#include <vector>
#include <queue>
#include <list>
#include <map>
#include <string>
#include <cstdio>

using namespace std;

int memo[100001];

int main(){
    int i,j,k,l,m,n;
    int c;
    
    cin >> n;
    
    m=0;c=1;
    for (i=0;i<n;i++){
        cin >> j;
        if (j==c){
            while (memo[++c]);
        }else{
            m++;
        }
        memo[j]=1;
    }
    
    cout << m << endl;
            
    
    return 0;
}