#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
#define ll long long
#define vi vector<int>
#define vvi vector<vi>
#define pb push_back
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define FORR(i, a, b) for(int i = a; i >= b; --i)
#define pii pair<int, int>
#define ff first
#define ss second
#define pll pair<ll, ll>
#define vpi vector<pii>
#define vvpi vector<vpi>
#define vpl vector<pll>
#define vvpl vector<vpl>
#define vl vector<ll>
#define vvl vector<vl>
//#define x first
//#define y second
using namespace std;
const int N = 1e6 + 9, LGV = 33, LGN = 21, Mod = 1e9 + 7;
const int Inf = 0x3f3f3f3f;
//const ll Inf = LLONG_MAX / 2;
const bool test_case = false;
//ifstream fin("input.txt");
//ofstream fout("output.txt");
//#define cin fin
//#define cout fout
ll n, a[N], b[N], d[N];
void solve()
{
cin >> n;
FOR(i, 1, n)cin >> a[i] >> b[i];
FOR(i, 1, n)d[i] = a[i] - b[i];
FOR(i, 1, n)d[i] += d[i - 1];
ll ans = 0;
///make sure that there is no 0
FOR(i, 1, n)
if(d[i] < 0)
ans -= d[i], d[i] = 0;
///make sure that no element surpasses last element
FOR(i, 1, n - 1)
if(d[i] > d[n])
ans += d[i] - d[n], d[i] = d[n];
priority_queue<ll> q;
FOR(i, 1, n - 1)
{
q.push(d[i]);
q.push(d[i]);
ans += q.top() - d[i];
q.pop();
}
while(!q.empty() && q.top() > d[n])
{
ans += q.top() - d[n];
q.pop();
}
///d[i] must be strictly increasing (i.e) no
cout << ans << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int t = 1;
if(test_case)cin >> t;
while(t --)solve();
return 0;
}
