// Har Har Mahadev
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define int long long
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define repin rep(i,0,n)
#define precise(i) cout<<fixed<<setprecision(i)
#define vi vector<int>
#define si set<int>
#define mii map<int,int>
#define take(a,n) for(int j=0;j<n;j++) cin>>a[j];
#define give(a,n) for(int j=0;j<n;j++) cout<<a[j]<<' ';
#define vpii vector<pair<int,int>>
#define db double
#define be(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define pob pop_back
#define ff first
#define ss second
#define lb lower_bound
#define ub upper_bound
#define bpc(x) __builtin_popcountll(x)
#define btz(x) __builtin_ctz(x)
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
typedef tree<pair<int, int>, null_type,less<pair<int, int> >, rb_tree_tag,tree_order_statistics_node_update> ordered_multiset;
const long long INF=1e18;
const long long M=1e9+7;
const long long MM=998244353;
int power( int N, int M){
int power = N, sum = 1;
if(N == 0) sum = 0;
while(M > 0){if((M & 1) == 1){sum *= power;}
power = power * power;M = M >> 1;}
return sum;
}
const int MAXN = 100005;
int Z = 1;
int ls, rs, lv, zp;
map<int, int> MP;
void fix_left(ll s) {
if (ls >= s) return;
auto it = MP.begin();
while (ls + it->second <= s) {
ls += it->second;
lv += ls * (next(it)->first - it->first);
MP.erase(it++);
}
it->second -= s - ls;
ls = s;
}
void fix_right(ll s) {
if (rs <= s) return;
auto it = --MP.end();
while (rs - it->second >= s) {
rs -= it->second;
MP.erase(it--);
}
it->second += s - rs;
rs = s;
}
void advance() {
ll lo = MP.begin()->first;
if (zp < lo) lv += ls * (zp - lo);
else lv += Z * (zp - lo);
ls -= Z, rs += Z;
MP[zp] += 2 * Z;
}
void solve()
{
int n;
cin >> n;
vi a(n);
vi b(n);
vi d(n);
int off = 0;
repin{
cin >> a[i] >> b[i];
d[i] = a[i]-b[i];
if(i)d[i] += d[i-1];
}
repin{
if(d[i] < 0)off -= d[i],d[i] = 0;
}
ls = -1;
rs = 1;
MP[d[0]] = 2;
rep(i,1,n){
zp = d[i];
fix_left(-i);
fix_right(0);
advance();
}
int fin = lv, s = ls;
for (auto it = MP.begin(); it->first < zp; it++) {
s += it->second;
fin += s * (min(next(it)->first,d.back()) - it->first);
}
cout << fin+off << '\n';
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
#ifdef NCR
init();
#endif
#ifdef SIEVE
sieve();
#endif
solve();
return 0;
}
