#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> ii;
typedef complex<ld> cp;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<cp> vcp;
typedef vector<ld> vld;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<vii> vvii;
#define fastIO ios::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define forw(i,l,r) for( int i = (l) ; i < (r) ; i++ )
#define forb(i,r,l) for( int i = (r) ; i >= (l) ; i-- )
#define log2i(x) (32 - __builtin_clz((x)) - 1)
#define log2ll(x) (64 - __builtin_clzll((x)) - 1)
#define Pi 3.141592653589793
#define sz(x) (int)x.size()
#define mt make_tuple
#define mp make_pair
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_front
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
const int N = 5e3+7;
int n;
ll ans=0;
int a[N],b[N],diff[N],d[N],dp[N][N];
priority_queue<ll> q;
int main() {
fastIO;
//freopen("test.inp","r",stdin);
//freopen("test.out","w",stdout);
cin >> n;
forw(i,1,n+1) {
cin >> a[i] >> b[i];
diff[i]=a[i]-b[i];
d[i]=d[i-1]+diff[i];
}
forw(i,1,n+1) {
q.push(min(max(d[i],0),d[n]));
q.push(min(max(d[i],0),d[n]));
if(q.top()>d[i]) ans+=q.top()-d[i];
if(d[n]<d[i]) ans+=d[i]-d[n];
q.pop();
}
cout << ans;
return 0;
}
