#include <bits/stdc++.h>
using namespace std;
template<class T, class U>
void ckmin(T &a, U b)
{
if (a > b) a = b;
}
template<class T, class U>
void ckmax(T &a, U b)
{
if (a < b) a = b;
}
#define MP make_pair
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define SZ(x) ((int) (x).size())
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
const int MAXN = 500013;
const int INF = 1000000007;
int N;
ll arr[MAXN];
ll net[MAXN];
ll ans;
vl vec;
int32_t main()
{
cout << fixed << setprecision(12);
cerr << fixed << setprecision(4);
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> N;
FOR(i, 1, N + 1)
{
int a, b;
cin >> a >> b;
arr[i] = a - b;
}
//you want to make everything >= 0, and you can move smth 1 left or 1 right at a time.
//+1 -1 => +1 +0
//-1 +1 => -1 +0
FOR(i, 1, N + 1)
{
arr[i] += arr[i - 1];
}
FOR(i, 1, N)
{
if (arr[i] < 0)
{
ans -= arr[i];
arr[i] = 0;
}
if (arr[i] > arr[N])
{
ans += (arr[i] - arr[N]);
arr[i] = arr[N];
}
ans += arr[i];
}
priority_queue<ll> pq;
FOR(i, 1, N)
{
pq.push(arr[i]);
pq.push(arr[i]);
pq.pop();
}
while(!pq.empty())
{
ans -= (pq.top());
pq.pop();
}
//make the sequence increasing. or equal. in each move you can change smth by 0 or 1.
cout << ans << '\n';
return 0;
//make all arr's positive, what's the cost?
}
