#include "railroad.h"
#include <bits/stdc++.h>
using namespace std;
#define rep(i, j, k) for (int i = j; i < (int)k; i++)
#define pb push_back
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef vector<int> vi;
const int N = 2e6 + 10;
int par[N];
int getPar(int v) { return v == par[v] ? v : par[v] = getPar(par[v]); }
bool merge(int a, int b) {
if ((a = getPar(a)) == (b = getPar(b))) return false;
return par[a] = b, true;
}
long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
s.pb(1e9);
t.pb(1);
vi me(all(s));
for (auto e : t) me.pb(e);
sort(all(me));
me.resize(unique(all(me)) - me.begin());
for (auto &e : s) e = lower_bound(all(me), e) - me.begin();
for (auto &e : t) e = lower_bound(all(me), e) - me.begin();
int n = s.size();
vi cnt(me.size());
iota(par, par + me.size(), 0);
rep(i, 0, n) {
merge(s[i], t[i]);
cnt[s[i]]++;
cnt[t[i]]--;
}
ll res = 0;
int local = 0;
rep(i, 0, me.size() - 1) {
local += cnt[i];
if (local < 0) {
merge(i, i + 1);
}
if (local > 0) {
res += 1ll * local * (me[i + 1] - me[i]);
merge(i, i + 1);
}
}
vi ind(me.size() - 1);
iota(all(ind), 0);
sort(all(ind),
[&](int a, int b) { return me[a + 1] - me[a] < me[b + 1] - me[b]; });
for (auto e : ind)
if (merge(e, e + 1)) res += me[e + 1] - me[e];
return res;
}
