#include "walk.h"
#include <bits/stdc++.h>
using namespace std;
int dist (array<int, 2> &a, array<int, 2> &b) {
return abs(a[0] - b[0]) + abs(a[1] - b[1]);
}
long long min_distance(std::vector<int> x, std::vector<int> h, std::vector<int> l, std::vector<int> r, std::vector<int> y, int src, int snk) {
vector<array<int, 2>> p;
int n = x.size(), m = y.size();
vector<vector<int>> adj;
vector<int> seg[n + m], S[n], E[n];
auto add = [&] (int i) {
adj.push_back({i});
seg[i].push_back(p.size());
};
auto add2 = [&] (int i, int j) {
adj.push_back({i, j});
seg[i].push_back(p.size());
seg[j].push_back(p.size());
};
for (int i = 0; i < n; ++i) {
add(i);
p.push_back({x[i], 0});
add(i);
p.push_back({x[i], h[i]});
}
for (int i = 0; i < m; ++i) {
add2(l[i], n + i);
p.push_back({x[l[i]], y[i]});
add2(r[i], n + i);
p.push_back({x[r[i]], y[i]});
S[l[i]].push_back(i);
E[r[i]].push_back(i);
}
set<array<int, 2>> s;
for (int i = 0; i < n; ++i) {
for (int v : S[i]) {
s.insert({y[v], v});
}
for (auto &v : s) {
if (v[0] > h[i]) {
break;
}
add2(i, n + v[1]);
p.push_back({x[i], v[0]});
}
for (int v : E[i]) {
s.erase({y[v], v});
}
}
priority_queue<pair<long long, int>> pq;
pq.push({0, 2 * src});
vector<long long> dis(adj.size(), 1e18);
dis[2 * src] = 0;
while (pq.size()) {
long long d = -pq.top().first;
int u = pq.top().second;
pq.pop();
if (d != dis[u]) {
continue;
}
for (int e : adj[u]) {
seg[e].erase(find(seg[e].begin(), seg[e].end(), u));
for (int v : seg[e]) {
int dd = dist(p[u], p[v]);
if (d + dd < dis[v]) {
dis[v] = d + dd;
pq.push({-dis[v], v});
}
}
}
}
return dis[2 * snk] == 1e18 ? -1 : dis[2 * snk];
}
