#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <algorithm>
using namespace std;
using ll = long long;
const int sz = 1 << 17;
const int MXN = 1e5;
struct node
{
ll lz = 0;
ll sum = 0;
ll tsum = 0;
};
vector<node> tree(2 * sz);
void pushup(int node)
{
int lc = 2 * node, rc = 2 * node + 1;
tree[node].sum = tree[lc].sum + tree[rc].sum, tree[node].tsum = tree[lc].tsum + tree[rc].tsum;
}
void pushdown(int node, int l, int r)
{
int mid = l + (r - l) / 2;
ll clz = tree[node].lz;
tree[node].lz = 0;
ll tsumsub = clz * (clz + 1) / 2;
int lc = 2 * node, rc = 2 * node + 1;
ll lnum = 1ll * (mid - l + 1), rnum = 1ll * (r - mid);
tree[lc].tsum += (clz * tree[lc].sum + tsumsub * lnum), tree[rc].tsum += (clz * tree[rc].sum + tsumsub * rnum);
tree[lc].sum += clz * lnum, tree[rc].sum += clz * rnum;
tree[lc].lz += clz, tree[rc].lz += clz;
}
void upd(int node, int l, int r, int a, int b)
{
if ((r < a) || (l > b)) return;
if ((a <= l) && (r <= b))
{
tree[node].lz++;
tree[node].sum += 1ll * (r - l + 1);
tree[node].tsum += tree[node].sum;
return;
}
pushdown(node, l, r);
int mid = l + (r - l) / 2;
int lc = 2 * node, rc = 2 * node + 1;
upd(lc, l, mid, a, b), upd(rc, mid + 1, r, a, b);
pushup(node);
}
ll rq(int node, int l, int r, int a, int b)
{
if ((r < a) || (l > b)) return 0;
if ((a <= l) && (r <= b)) return tree[node].tsum;
pushdown(node, l, r);
int mid = l + (r - l) / 2;
int lc = 2 * node, rc = 2 * node + 1;
return rq(lc, l, mid, a, b) + rq(rc, mid + 1, r, a, b);
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<pair<int, int>> sails(n);
for (int i = 0; i < n; i++) cin >> sails[i].first >> sails[i].second;
sort(sails.begin(), sails.end());
for (pair<int, int> sail : sails)
{
int h = sail.first, k = sail.second;
ll lownum = rq(1, 0, MXN, h - k, h - k);
int cl = 0, cr = h - k;
while (cl < cr)
{
int mid = cl + (cr - cl) / 2;
if (rq(1, 0, MXN, mid, mid) > lownum) cl = mid + 1;
else cr = mid;
}
int fl = h - k, fr = h - 1;
while (fl < fr)
{
int mid = fl + (fr - fl + 1) / 2;
if (rq(1, 0, MXN, mid, mid) < lownum) fr = mid - 1;
else fl = mid;
}
int numlowadd = fl - (h - k) + 1;
upd(1, 0, MXN, cl, cl + numlowadd - 1), upd(1, 0, MXN, fl + 1, h - 1);
}
cout << tree[1].tsum - tree[1].sum;
}
