#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
int a[400400];
int b[400400];
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
	int n;
	cin>>n;
	for(int i = 1;i<=n;i++)
	{
		cin>>a[i];
	}
	for(int i = 1;i<=n;i++)
	{
		cin>>b[i];
	}
	int cnt = 0;
	for(int i = 1;i<=n;i++)
	{
		int minn = 1e9;
		int m;
		for(int j = 1;j<=n;j++)
		{
			if(a[j] > b[i])
			{
				if(a[j] < minn)
				{
					minn = a[j];
					m = j;
				}
			}
		}
		if(minn == 1e9)
		{
			continue;
		}
		else
		{
			cnt++;
			a[m] = 0;
		}
	}
	cout<<cnt;
    return 0;
}