#include "railroad.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9;
ll rel_val[400005];
int in_[400005];
int out_[400005];
int rep_[400005];
int fint(int v)
{
if(rep_[v] == v) return v;
rep_[v] = fint(rep_[v]);
return rep_[v];
}
void onion(int a, int b)
{
rep_[fint(a)] = fint(b);
}
ll plan_roller_coaster(vi s, vi t)
{
int n = siz(s)+1;
s.pb(1);
t.pb(1e9);
ll ans = 0;
map<int,int> m;
rep(i,n)
{
m[s[i]] = 1;
m[t[i]] = 1;
}
int cur = 0;
forall(it,m)
{
rel_val[cur] = it.ff;
m[it.ff] = cur++;
}
rep(i,n)
{
s[i] = m[s[i]];
t[i] = m[t[i]];
}
rep(i,cur) rep_[i] = i;
rep(i,n)
{
onion(s[i],t[i]);
in_[t[i]]++;
out_[s[i]]++;
}
int bal = 0;
rep(j,cur)
{
bal -= in_[j];
bal += out_[j];
if(bal > 0)
{
onion(j,j+1);
ans += bal * (rel_val[j+1] - rel_val[j]);
bal--;
}
else if(bal < 0)
{
onion(j,j+1);
bal--;
}
}
vector<pair<ll,pii>> edges;
rep(j,cur-1)
{
if(fint(j) != fint(j+1))
{
edges.pb({rel_val[j+1]-rel_val[j],{j,j+1}});
}
}
sort(all(edges));
forall(it,edges)
{
if(fint(it.ss.ff) != fint(it.ss.ss))
{
ans += it.ff;
onion(it.ss.ff,it.ss.ss);
}
}
return ans;
}
