/* #region Head */

// #include <bits/stdc++.h>
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert> // assert.h
#include <cmath>   // math.h
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pll = pair<ll, ll>;
template <class T> using vc = vector<T>;
template <class T> using vvc = vc<vc<T>>;
using vll = vc<ll>;
using vvll = vvc<ll>;
using vld = vc<ld>;
using vvld = vvc<ld>;
using vs = vc<string>;
using vvs = vvc<string>;
template <class T, class U> using um = unordered_map<T, U>;
template <class T> using pq = priority_queue<T>;
template <class T> using pqa = priority_queue<T, vc<T>, greater<T>>;
template <class T> using us = unordered_set<T>;

#define TREP(T, i, m, n) for (T i = (m), i##_len = (T)(n); i < i##_len; ++(i))
#define TREPM(T, i, m, n) for (T i = (m), i##_max = (T)(n); i <= i##_max; ++(i))
#define TREPR(T, i, m, n) for (T i = (m), i##_min = (T)(n); i >= i##_min; --(i))
#define TREPD(T, i, m, n, d)                                                   \
    for (T i = (m), i##_len = (T)(n); i < i##_len; i += (d))
#define TREPMD(T, i, m, n, d)                                                  \
    for (T i = (m), i##_max = (T)(n); i <= i##_max; i += (d))

#define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i))
#define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i))
#define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i))
#define REPD(i, m, n, d)                                                       \
    for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d))
#define REPMD(i, m, n, d)                                                      \
    for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d))
#define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
#define REPIR(itr, ds) for (auto itr = ds.rbegin(); itr != ds.rend(); itr++)
#define ALL(x) begin(x), end(x)
#define SIZE(x) ((ll)(x).size())
#define ISIZE(x) ((int)(x).size())
#define PERM(c)                                                                \
    sort(ALL(c));                                                              \
    for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c)))
#define UNIQ(v) v.erase(unique(ALL(v)), v.end());
#define CEIL(a, b) (((a) + (b)-1) / (b))

#define endl '\n'

constexpr ll INF = 1'010'000'000'000'000'017LL;
constexpr int IINF = 1'000'000'007LL;
constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7
// constexpr ll MOD = 998244353;
constexpr ld EPS = 1e-12;
constexpr ld PI = 3.14159265358979323846;

// 前方宣言
template <typename T> istream &operator>>(istream &is, vc<T> &vec);
template <typename T> ostream &operator<<(ostream &os, const vc<T> &vec);
template <typename T> ostream &operator>>(ostream &os, const vc<T> &vec);
template <typename T, size_t _Nm>
istream &operator>>(istream &is, array<T, _Nm> &arr);
template <typename T, size_t _Nm>
ostream &operator<<(ostream &os, const array<T, _Nm> &arr);
template <typename T, size_t _Nm>
ostream &operator>>(ostream &os, const array<T, _Nm> &arr);
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &pair_var);
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &pair_var);
template <class T> ostream &out_iter(ostream &os, const T &map_var);
template <typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &map_var);
template <typename T, typename U>
ostream &operator<<(ostream &os, const um<T, U> &map_var);
template <typename T> ostream &operator<<(ostream &os, const set<T> &set_var);
template <typename T> ostream &operator<<(ostream &os, const us<T> &set_var);
template <typename T> ostream &operator<<(ostream &os, const pq<T> &pq_var);
template <typename T>
ostream &operator<<(ostream &os, const queue<T> &queue_var);
template <typename T> ostream &operator<<(ostream &os, const stack<T> &stk_var);

template <typename T>
istream &operator>>(istream &is, vc<T> &vec) { // vector 入力
    for (T &x : vec)
        is >> x;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vc<T> &vec) { // vector 出力 (for dump)
    os << "{";
    REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "" : ", ");
    os << "}";
    return os;
}
template <typename T>
ostream &operator>>(ostream &os, const vc<T> &vec) { // vector 出力 (inline)
    REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "\n" : " ");
    return os;
}

template <typename T, size_t _Nm>
istream &operator>>(istream &is, array<T, _Nm> &arr) { // array 入力
    REP(i, 0, SIZE(arr)) is >> arr[i];
    return is;
}
template <typename T, size_t _Nm>
ostream &operator<<(ostream &os,
                    const array<T, _Nm> &arr) { // array 出力 (for dump)
    os << "{";
    REP(i, 0, SIZE(arr)) os << arr[i] << (i == i_len - 1 ? "" : ", ");
    os << "}";
    return os;
}

template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &pair_var) { // pair 入力
    is >> pair_var.first >> pair_var.second;
    return is;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &pair_var) { // pair 出力
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}

// map, um, set, us 出力
template <class T> ostream &out_iter(ostream &os, const T &map_var) {
    os << "{";
    REPI(itr, map_var) {
        os << *itr;
        auto itrcp = itr;
        if (++itrcp != map_var.end())
            os << ", ";
    }
    return os << "}";
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &map_var) {
    return out_iter(os, map_var);
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const um<T, U> &map_var) {
    os << "{";
    REPI(itr, map_var) {
        auto [key, value] = *itr;
        os << "(" << key << ", " << value << ")";
        auto itrcp = itr;
        if (++itrcp != map_var.end())
            os << ", ";
    }
    os << "}";
    return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &set_var) {
    return out_iter(os, set_var);
}
template <typename T> ostream &operator<<(ostream &os, const us<T> &set_var) {
    return out_iter(os, set_var);
}
template <typename T> ostream &operator<<(ostream &os, const pq<T> &pq_var) {
    pq<T> pq_cp(pq_var);
    os << "{";
    if (!pq_cp.empty()) {
        os << pq_cp.top(), pq_cp.pop();
        while (!pq_cp.empty())
            os << ", " << pq_cp.top(), pq_cp.pop();
    }
    return os << "}";
}

// tuple 出力
template <size_t N = 0, bool end_line = false, typename... Args>
ostream &operator<<(ostream &os, tuple<Args...> &a) {
    if constexpr (N < std::tuple_size_v<tuple<Args...>>) {
        os << get<N>(a);
        if constexpr (N + 1 < std::tuple_size_v<tuple<Args...>>) {
            os << ' ';
        } else if constexpr (end_line) {
            os << '\n';
        }
        return operator<< <N + 1, end_line>(os, a);
    }
    return os;
}
template <typename... Args> void print_tuple(tuple<Args...> &a) {
    operator<< <0, true>(std::cout, a);
}

void pprint() { std::cout << endl; }
template <class Head, class... Tail> void pprint(Head &&head, Tail &&...tail) {
    std::cout << head;
    if (sizeof...(Tail) > 0)
        std::cout << ' ';
    pprint(move(tail)...);
}

// dump
#define DUMPOUT cerr
void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&...tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0)
        DUMPOUT << ", ";
    dump_func(move(tail)...);
}

// chmax (更新「される」かもしれない値が前)
template <typename T, typename U, typename Comp = less<>>
bool chmax(T &xmax, const U &x, Comp comp = {}) {
    if (comp(xmax, x)) {
        xmax = x;
        return true;
    }
    return false;
}

// chmin (更新「される」かもしれない値が前)
template <typename T, typename U, typename Comp = less<>>
bool chmin(T &xmin, const U &x, Comp comp = {}) {
    if (comp(x, xmin)) {
        xmin = x;
        return true;
    }
    return false;
}

// ローカル用
#ifndef ONLINE_JUDGE
#define DEBUG_
#endif

#ifndef MYLOCAL
#undef DEBUG_
#endif

#ifdef DEBUG_
#define DEB
#define dump(...)                                                              \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
            << endl                                                            \
            << "    ",                                                         \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

#define VAR(type, ...)                                                         \
    type __VA_ARGS__;                                                          \
    assert((std::cin >> __VA_ARGS__));

template <typename T> istream &operator,(istream &is, T &rhs) {
    return is >> rhs;
}
template <typename T> ostream &operator,(ostream &os, const T &rhs) {
    return os << ' ' << rhs;
}

struct AtCoderInitialize {
    static constexpr int IOS_PREC = 15;
    static constexpr bool AUTOFLUSH = false;
    AtCoderInitialize() {
        ios_base::sync_with_stdio(false), std::cin.tie(nullptr),
            std::cout.tie(nullptr);
        std::cout << fixed << setprecision(IOS_PREC);
        if (AUTOFLUSH)
            std::cout << unitbuf;
    }
} ATCODER_INITIALIZE;

void Yn(bool p) { std::cout << (p ? "Yes" : "No") << endl; }
void YN(bool p) { std::cout << (p ? "YES" : "NO") << endl; }

template <typename T> constexpr void operator--(vc<T> &v, int) noexcept {
    for (int i = 0; i < ISIZE(v); ++i)
        v[i]--;
}
template <typename T> constexpr void operator++(vc<T> &v, int) noexcept {
    for (int i = 0; i < ISIZE(v); ++i)
        v[i]++;
}

/* #endregion */

// #include <atcoder/all>
// using namespace atcoder;

/* #region Graph */

// エッジ（本来エッジは双方向だが，ここでは単方向で管理）
template <class weight_t = int, class flow_t = int> struct Edge {
    int src;         // エッジ始点となる頂点
    int dst;         // エッジ終点となる頂点
    weight_t weight; // 重み
    flow_t cap;
    Edge() : src(0), dst(0), weight(0) {}
    Edge(int src, int dst, weight_t weight)
        : src(src), dst(dst), weight(weight) {}
    Edge(int src, int dst, weight_t weight, flow_t cap)
        : src(src), dst(dst), weight(weight), cap(cap) {}
    // Edge 標準出力
    friend ostream &operator<<(ostream &os, Edge &edge) {
        os << "(" << edge.src << " -> " << edge.dst << ", " << edge.weight
           << ")";
        return os;
    }
};

// 同じ頂点を始点とするエッジ集合
template <class weight_t = int, class flow_t = int>
class Node : public vc<Edge<weight_t, flow_t>> {
  public:
    int idx;
    Node() : vc<Edge<weight_t, flow_t>>() {}
    // void add(int a, int b, weight_t w, flow_t cap) { this->emplace_back(a, b,
    // w, cap); };
};

// graph[i] := 頂点 i を始点とするエッジ集合
template <class weight_t = int, class flow_t = int>
class Graph : public vc<Node<weight_t, flow_t>> {
  public:
    Graph() : vc<Node<weight_t, flow_t>>() {}
    Graph(int n) : vc<Node<weight_t, flow_t>>(n) {
        REP(i, 0, n)(*this)[i].idx = i;
    }
    /** 単方向 */
    void add_arc(int a, int b, weight_t w = 1, flow_t cap = 1) {
        (*this)[a].emplace_back(a, b, w, cap);
    }
    /** 双方向 */
    void add_edge(int a, int b, weight_t w = 1, flow_t cap = 1) {
        add_arc(a, b, w, cap), add_arc(b, a, w, cap);
    }
    /** ノード追加 */
    int add_node() {
        int idx = (int)this->size();
        this->emplace_back();
        Node<weight_t, flow_t> &node = this->back();
        node.idx = idx;
        return idx;
    }
};
// using Array = vc<Weight>;
// using Matrix = vc<Array>;

/* #endregion */

template <class Weight = ll> struct BFSGraph {
    // pair 比較よりも struct 比較のほうが速い
    struct state {
        Weight cost;
        int dst;
        state(Weight cost, int dst) : cost(cost), dst(dst) {}
        bool operator<(const state &o) const { return cost > o.cost; }
        // bool operator>(const state &o) const { return cost > o.cost; }
    };

    Graph<Weight> graph;
    vc<Weight> dist;
    vc<int> bs; // 経路復元用情報
    Weight inf;

    /** コンストラクタ */
    BFSGraph(const int n, const Weight inf = INF)
        : graph(n), dist(n, inf), bs(n, -1), inf(inf) {}
    /** コンストラクタ，グラフを使って初期化するバージョン */
    BFSGraph(const Graph<Weight> &graph, const Weight inf = INF)
        : graph(graph), dist(graph.size(), inf), bs(graph.size(), -1),
          inf(inf) {}

    // 有向辺の追加
    void add_edge(int src, int dst, Weight cost) {
        graph.add_arc(src, dst, cost);
    }

    void build(int start, Weight init = 0) {
        queue<state> que; // FIFO
        fill(ALL(dist), inf);
        fill(ALL(bs), -1);
        dist[start] = init;
        que.emplace(init, start);
        while (que.size()) {
            const state cur = que.front(); // tie(d, v) = que.top();
            que.pop();
            int cur_node = cur.dst;
            Weight cur_cost = cur.cost;

            if (dist[cur_node] < cur_cost)
                continue;
            for (const Edge<Weight> &edge : graph[cur_node])
                if (chmin(dist[edge.dst], dist[cur_node] + edge.weight)) {
                    que.emplace(dist[edge.dst], edge.dst);
                    bs[edge.dst] = cur_node;
                }
        }
    }

    // あるノードまでの距離を返す
    Weight operator[](const int dst) const { return dist[dst]; }

    // 経路復元
    // dst がスタート地点の場合は空ベクトルが返るため注意
    vc<int> restore(int dst) const {
        vc<int> res;
        if (bs[dst] < 0)
            return res;
        while (~dst)
            res.emplace_back(dst), dst = bs[dst];
        reverse(ALL(res));
        return res;
    }
};

// Problem
void solve() {
    VAR(ll, n, q);
    vll a(n), b(q);
    cin >> a, b;

    map<ll, vll> indices;
    REP(i, 0, n) {
        indices[a[i]].push_back(i); //
    }

    // 0 から．移動先候補は「同じ位置」か，「両隣」に絞っても損しない．
    BFSGraph<> graph(n * (q + 1), INF);
    ll prev_value = a[0];
    REP(i, 0, q) {
        // 遷移元ごとに
        for (const auto &idx_from : indices[prev_value]) {
            auto ub = lower_bound(ALL(indices[b[i]]), idx_from);
            if (ub != indices[b[i]].end()) {
                const int idx_ub = *ub;
                graph.add_edge(n * i + idx_from, n * (i + 1) + idx_ub,
                               abs(idx_ub - idx_from));
            }
            if (ub != indices[b[i]].begin()) {
                ub--;
                const int idx_lb = *ub;
                graph.add_edge(n * i + idx_from, n * (i + 1) + idx_lb,
                               abs(idx_lb - idx_from));
            }
        }
        prev_value = b[i];
    }

    graph.build(0);

    // 最小値を求める
    ll ans = INF;
    REP(i, 0, n) {
        if (graph.dist[n * q + i] != INF) {
            chmin(ans, graph.dist[n * q + i]);
        }
    }
    pprint(ans);
}

// entry point
int main() {
    solve();
    return 0;
}