#pragma GCC target ("avx2")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define FAST_IO ios_base::sync_with_stdio(0); cin.tie(0)
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define REP(n) FOR(O, 1, (n))
#define pb push_back
#define f first
#define s second
typedef long double ld;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<int, pii> piii;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<piii> viii;
const int MAXN = 500100, MAXK = 30;
//const ll MOD = 998244353;
const ll INF = 4e18;
const ld PI = asin(1) * 2;
int n;
ll a[MAXN], b[MAXN], dif[MAXN], pref[MAXN];
ll dp[2][31000];
int main()
{
FAST_IO;
cin >> n;
FOR(i, 1, n) cin >> a[i] >> b[i];
FOR(i, 1, n) {
dif[i] = a[i]-b[i];
pref[i] = pref[i-1] + dif[i];
}
priority_queue<ll> q;
ll ans = 0;
FOR(i, 1, n) {
REP(2) q.push(max(0ll, pref[i]));
q.pop();
ans += abs(pref[i]);
}
while (!q.empty()) {
ans -= min(pref[n], q.top());
q.pop();
}
cout << ans << "\n";
return 0;
}
