abc273f WA

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#define dbg(...) logger(#__VA_ARGS__, __VA_ARGS__)
template <typename... Args> void logger(string vars, Args &&... values)
{
    cerr << vars << " = ";
    string delim = "";
    (..., (cerr << delim << values, delim = ", "));
    cerr << endl;
}

template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using piii = pair<int, pii>;

int n;
vector<piii> events;
vector<vector<pll>> dp;
vector<int> key_contains;
int ori = 0;
int dest = 0;

ll search(int beg, int end, int dir)
{
    if (dir == 0 && dp[beg][end].first < LLONG_MAX)
        return dp[beg][end].first;
    if (dir == 1 && dp[beg][end].second < LLONG_MAX)
        return dp[beg][end].second;
    if (beg > end)
        return LLONG_MAX / 2;
    ll ans = LLONG_MAX / 2;
    if (dir) {
        int wtype = events[end].second.first;
        if ((events[end].second.second == 1 && beg <= key_contains[wtype] && end - 1 >= key_contains[wtype]) ||
            (events[end].second.second == 0 || events[end].second.second == 2 || events[end].second.second == -1)) {
            ans = min(search(beg, end - 1, 0) + events[end].first - events[beg].first,
                      search(beg, end - 1, 1) + events[end].first - events[end - 1].first);
        }
        return dp[beg][end].second = ans;
    } else {
        int wtype = events[beg].second.first;
        if ((events[beg].second.second == 1 && beg + 1 <= key_contains[wtype] && end >= key_contains[wtype]) ||
            (events[beg].second.second == 0 || events[beg].second.second == 2 || events[beg].second.second == -1)) {
            ans = min(search(beg + 1, end, 0) + events[beg + 1].first - events[beg].first,
                      search(beg + 1, end, 1) + events[end].first - events[beg].first);
        }
        return dp[beg][end].first = ans;
    }
    return ans;
}

int main(int argc, char **argv)
{
    int x;
    scanf("%d%d", &n, &x);
    events.push_back({0, {0, -1}});
    events.push_back({x, {0, 0}});
    for (int i = 1; i <= n; ++i)
        scanf("%d", &x), events.push_back({x, {i, 1}});
    for (int i = 1; i <= n; ++i)
        scanf("%d", &x), events.push_back({x, {i, 2}});

    sort(events.begin(), events.end());
    int nn = events.size();
    key_contains = vector<int>(nn, -1);
    for (int i = 0; i < nn; ++i)
        if (events[i].second.first == 0)
            if (events[i].second.second == -1)
                ori = i;
            else
                dest = i;
        else if (events[i].second.second == 2)
            key_contains[events[i].second.first] = i;

    dp = vector<vector<pll>>(nn + 1, vector<pll>(nn + 1, {LLONG_MAX, LLONG_MAX}));
    dp[ori][ori] = {0, 0};

    search(0, nn - 1, 0);
    search(0, nn - 1, 1);

    ll min_val = LLONG_MAX;
    dbg(ori, dest);
    if (ori < dest)
        min_val = min(dp[ori][dest].first, dp[ori][dest].second), dbg(dp[ori][dest].first, dp[ori][dest].second);
    else
        min_val = min(dp[dest][ori].first, dp[dest][ori].second), dbg(dp[dest][ori].first, dp[dest][ori].second);

    printf("%lld\n", min_val >= LLONG_MAX / 2 ? -1ll : min_val);

    return 0;
};