#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define pi pair<int,int>
#define sz(v) (int)(v).size()
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
template<class T> using upq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int lwrbound(const vector<T>& a, const T& b, const int s = 0){return int(lower_bound(s + all(a), b) - a.begin());}
template<class T> int uprbound(const vector<T>& a, const T& b, const int s = 0){return int(upper_bound(s + all(a), b) - a.begin());}
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define ROF(i, a, b) for(int i = (a); i >= (b); i--)
#define sumof(x) accumulate(all(x), 0ll)
#define dbg(x) "[" << #x " = " << (x) << "]"
#define el "\n"
using ll = long long;
using ld = long double;
template<class T> bool ckmx(T& a, const T b){return (a < b ? a = b, true : false);}
template<class T> bool ckmn(T& a, const T b){return (a > b ? a = b, true : false);}
const int N = 1e5 + 5;
ll dif[N], cnt[N], stk[N], _tp;
void Main()
{
int n; cin >> n;
FOR(i, 1, n){
int h,k; cin >> h >> k;
dif[h - k + 1] += 1ll * k, dif[h + 1] -= 1ll * k;
}
_tp = -1;
FOR(i, 1, N){
dif[i] += dif[i - 1];
ll ccnt = dif[i];
ll sum = dif[i], lp = i;
while(_tp > - 1 && cnt[stk[_tp]] < ccnt){
sum += 1ll * (lp - stk[_tp]) * cnt[stk[_tp]];
ccnt = (sum + (i - stk[_tp] - 1)) / (i - stk[_tp]);
lp = stk[_tp--];
}
if(_tp < 0 || cnt[stk[_tp]] != ccnt){
stk[++_tp] = lp, cnt[lp] = ccnt;
if(ccnt * (i - lp) > sum){
--ccnt;
sum -= 1ll * (i - lp) * ccnt;
lp = lp + sum - 1;
stk[++_tp] = lp, cnt[lp] = ccnt;
}
}
}
auto f = [&](ll x) -> ll{
return 1ll * x * (x + 1) / 2;
};
ll lp = n + 1, ans = 0;
while(_tp >= 0){
ans += 1ll * (lp - stk[_tp]) * f(cnt[stk[_tp]]);
lp = stk[_tp--];
}
cout << ans << el;
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define name "InvMOD"
if(fopen(name".INP", "r")){
freopen(name".INP", "r", stdin);
freopen(name".OUT", "w", stdout);
}
int t = 1; while(t--) Main();
return 0;
}
