#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n,m;
    cin>>n>>m;
    vector<int> v, v2;
    priority_queue<int, vector<int>, greater<int>> q;
    priority_queue<int> pq;
    for (int i=0;i<n;i++){
        int a;
        cin>>a;
        v.push_back(a);
        v2.push_back(a);
    }
    for (int i=0;i<m;i++){
        int a;
        cin>>a;
        q.push(a);
        pq.push(a);
    }
    int curr=v[0];
    int ans=0;
    for (int i=1; i<n;i++){
        if (curr>=v[i]){
            while (q.top()<=curr && !q.empty()){
                q.pop();
            }
            if (q.empty()){
                ans=1e9;
                break;


            }
            v[i]=q.top();
            ans++;
        }
        curr=v[i];
    }
    int ans2=0;
    curr=v2[n-1];
    for (int i=n-2;i>=0;i--){
        if (curr<=v2[i]){
            while (pq.top()>=curr && !pq.empty()){
                pq.pop();
            }
            if (pq.empty()){
                ans2=1e9;

                break;
            }
            v2[i]=pq.top();
            ans2++;
        }
        curr=v2[i];
    }
    cout<<min(ans, ans2);
}