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

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

template<class T> ostream& operator << (ostream& os, const vector<T>& vec) {
    if(vec.empty()) return os;
    os << vec[0];
    for(auto it = vec.begin(); ++it != vec.end(); ) os << ' ' << *it;
    return os;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, q;
    cin >> n >> q;
    vector<int> c(n), ca;
    for(int i = 0; i < n; i++){
        cin >> c[i];
    }
    ca = c;
    sort(ca.begin(), ca.end());
    vector<vector<int>> tb(ca.size());
    for(int i = 0; i < n; i++){
        int p = lower_bound(ca.begin(), ca.end(), c[i]) - ca.begin();
        tb[p].emplace_back(i);
    }
    vector<ll> ldp(n, 1ll << 60), rdp(n, 1ll << 60);
    ldp[0] = 0;
    for(int i = 0; i + 1 < n; i++){
        ldp[i + 1] = min(ldp[i + 1], ldp[i]);
    }
    for(int i = 0; i < q; i++){
        vector<ll> ldp2(n, 1ll << 60);
        vector<ll> rdp2(n, 1ll << 60);
        int v;
        cin >> v;
        v = lower_bound(ca.begin(), ca.end(), v) - ca.begin();

        for(auto &&p : tb[v]){
            ll mn = min(ldp[p] + p, rdp[p] - p);
            ldp2[p] = mn - p;
            rdp2[p] = mn + p;
        }
        for(int i = 0; i + 1 < n; i++){
            ldp2[i + 1] = min(ldp2[i + 1], ldp2[i]);
        }
        for(int i = n - 1; i >= 1; i--){
            rdp2[i - 1] = min(rdp2[i - 1], rdp2[i]);
        }
        swap(rdp, rdp2);
        swap(ldp, ldp2);
    }
    ll ans = 1ll << 60;
    for(int i = 0; i < n; i++){
        ans = min(ans, ldp[i] + i);
        ans = min(ans, rdp[i] - i);
    }
    cout << ans << '\n';
}