#include "bits/stdc++.h"
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using str = string;
using ld = long double;
using db = double;
//--------------------
#define F first
#define S second
#define pb push_back
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define mem(f,x) memset(f , x , sizeof(f))
#define __lcm(x, y) (1LL * ((x) / __gcd((x), (y))) * (y))
template<class T> bool maximize(T &a,const T &b){ return (a < b ? a = b, 1 : 0); }
template<class T> bool minimize(T &a,const T &b){ return (a > b ? a = b, 1 : 0); }
//--------------------
#define PROBLEM "test"
const int MOD = 1e9 + 7; // 998244353;
const ll INF = 1e18;
const db PI = acos(-1);
const int dx[4]{0, 1, 0, -1}, dy[4]{1, 0, -1, 0}; // U R D L
const int ddx[4]{-1, 1, 1, -1}, ddy[4]{1, 1, -1, -1}; // UR DR DL UL
const int kx[8]{1, 1, 2, 2, -1, -1, -2, -2}, ky[8]{-2, 2, -1, 1, -2, 2, -1, 1};
//-----------------[PROBLEM SOLUTION]-----------------//
void solve() {
ll n, res = 0, pref = 0;
cin >> n;
ll x, y;
priority_queue<ll> pq;
for (int i = 0; i < n; i++) pq.push(0);
for (int i = 0; i < n - 1; i++) {
cin >> x >> y;
pref += x - y;
pq.push(pref);
if (pref < pq.top()) {
res += pq.top() - pref;
pq.pop(); pq.push(pref);
}
}
cin >> x >> y;
pref += x - y;
while(pq.size() && pref < pq.top())
res += pq.top() - pref, pq.pop();
cout << res << '\n';
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(PROBLEM".inp", "r")){
freopen(PROBLEM".inp", "r", stdin);
freopen(PROBLEM".out", "w", stdout);
}
constexpr bool MULTI_TEST = 0;
int t = 1;
if(MULTI_TEST) cin >> t;
while(t--)
solve();
}
