#include<map>

#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

using namespace std;

int n,ans;

int a[];

int num[],pos[];

int main(){

    scanf("%d",&n);

    for(int i=;i<=n;i++)    scanf("%d",&num[i]),pos[num[i]]++;

    for (int i=;i<=pos[]+pos[];i++){

        if(num[i]==) a[]++;

        else if(num[i]==&&i<=pos[]) a[]++;

        else if(num[i]==&&i>pos[]) a[]++;

    }

    cout<<a[]+(a[]>a[]?a[]:a[])<<endl;

}