#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long

using namespace std;

int main() {
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    ll n, m;
    cin >> n >> m;
    vector<ll>items(n);
    map<ll,ll>mp;
    for (int i=0; i<n; i++) {
        cin >> items[i];
        mp[items[i]]++;
    }
    vector<ll>cars(m);
    for (int i=0; i<m; i++) {
        cin >> cars[i];
    }
    vector<vector<ll>>v(m);
    sort(items.begin(), items.end());
    sort(cars.rbegin(), cars.rend());
    ll ans=0;
    while (!mp.empty()) {
        auto x=--mp.rbegin();
        int i=0;
        while (i<m) {
            if (x->first<=cars[i]) {
                i++;
                if (x->second>1) x->second--;
                else mp.erase(x->first);
                if (mp.empty()) break;
            }
            else if (x!=mp.rend()) x++;
            else break;
        }
        ans+=2;
    }
    ans--;
    cout << ans << endl;
    return 0;
}