#include<bits/stdc++.h>
using namespace std;
int n,m,i,j,d;long long a[100001],b[100001];
int main()
{
    cin>>n>>m;
    for (i=1;i<=n;i++) cin>>a[i];
    for (i=1;i<=m;i++) cin>>b[i];
    sort(a+1,a+1+n,greater<int>());
    sort(b+1,b+1+m,greater<int>());i=1;j=1;
    while (j<=m && i<=n)
       if (a[i]>b[j]){i++;j++;d++;}
       else j++;
    cout<<d;
}