#include "railroad.h"
/* Ignore Others Only Focus On Yourself! */
/* Im the Best! */
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define Mp make_pair
#define point complex
#define endl '\n'
#define SZ(x) (int)x.size()
#define fast_io ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define file_io freopen("input.txt", "r+", stdin); freopen("output.txt", "w+", stdout);
#define mashtali return cout << "Hello, World!", 0;
const int N = 1e6 + 10;
const int LOG = 20;
const ll mod = 1e9 + 7;
const ll inf = 8e18;
const double pi = acos(-1);
const ld eps = 1e-18;
const ld one = 1.;
ll pw(ll a, ll b, ll M, ll ret = 1) { if(a == 0) return 0; a %= M; while(b) { ret = (b & 1? ret * a % M : ret), a = a * a % M, b >>= 1; } return ret % M; }
mt19937 rng(time(nullptr));
vector < int > cm;
int ps[N], par[N];
int get(int x)
{
return (x == par[x]? x : par[x] = get(par[x]));
}
int unify(int v, int u)
{
v = get(v), u = get(u);
if(v == u) return 0;
par[u] = v;
return 1;
}
int lwr(int x)
{
return lower_bound(all(cm), x) - cm.begin();
}
ll plan_roller_coaster(vector < int > s, vector < int > t)
{
iota(par, par + N, 0);
int n = SZ(s);
for(int i = 0; i < n; i ++)
{
cm.push_back(s[i]);
cm.push_back(t[i]);
}
cm.push_back(-1e9 - 5);
cm.push_back(1e9 + 5);
sort(all(cm));
cm.resize(unique(all(cm)) - cm.begin());
for(int i = 0; i < n; i ++)
{
s[i] = lwr(s[i]);
t[i] = lwr(t[i]);
ps[s[i]] --;
ps[t[i]] ++;
unify(s[i], t[i]);
}
ll tot = 0;
vector < pll > E;
for(int i = 0; i < SZ(cm) - 1; i ++)
{
ps[i + 1] += ps[i];
tot += 1ll * max(0, -1 - ps[i]) * (cm[i + 1] - cm[i]);
if(ps[i] == -1)
{
E.push_back(Mp(cm[i + 1] - cm[i], i));
}
else
{
unify(i, i + 1);
}
}
sort(all(E));
for(auto [c, i] : E)
{
if(unify(i, i + 1))
{
tot += c;
}
}
return tot;
}
