#include<bits/stdc++.h>
using namespace std;
const int N=5e4+5; 
int n,ans=0; 
int a[N],b[N];
int main(){
    cin>>n;
    for (int i=1;i<=n;i++) cin>>b[i];
    for (int i=1;i<=n;i++) cin>>a[i];
    sort(a+1,a+1+n);
    sort(b+1,b+1+n);
    for (int i=1;i<=n;i++){
    	for (int j=n;j>=1;j--){
    		if (a[j]<b[i]){
    			a[j]=1e9;
    			b[i]=-1e9;
    			ans++;
			}
		}
	}
	cout<<ans;
	return 0;
}