#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int mxN = 4e5+10;
ll st[mxN], st1[mxN], lazy[mxN];
void push(int node, int l, int r) {
if(l == r) return ;
int left = node*2, right = node*2+1, mid = (l+r)/2;
lazy[left] += lazy[node]; lazy[right] += lazy[node];
st[left] += lazy[node] * (mid - l + 1);
st[right] += lazy[node] * (r - mid);
st1[left] += lazy[node]; st1[right] += lazy[node];
lazy[node] = 0;
}
ll qry(int node, int l, int r, int l1, int r1) {
push(node, l, r);
if(l1 <= l && r <= r1) return st[node];
if(l1 > r || r1 < l) return 0LL;
int mid = (l+r)/2;
return qry(node*2, l, mid, l1, r1) + qry(node*2+1, mid+1, r, l1, r1);
st[node] = st[node*2] + st[node*2+1];
st1[node] = max(st1[node*2], st1[node*2+1]);
}
void upd(int node, int l, int r, int l1, int r1) {
push(node, l, r);
if(l1 <= l && r <= r1) {
st[node] += (r-l+1);
lazy[node]++;
return ;
}
if(l > r1 || r < l1) return ;
int mid = (l+r)/2;
upd(node*2, l, mid, l1, r1);
upd(node*2+1, mid+1, r, l1, r1);
st[node] = st[node*2] + st[node*2+1];
st1[node] = max(st1[node*2], st1[node*2+1]);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, H = 0;
cin >> n;
vector<array<int, 2>> v(n);
for(int i = 0; i < n; i++) {
cin >> v[i][0] >> v[i][1];
H = max(H, v[i][0]);
}
const auto first_val = [&](int val, int l, int r) {
++r;
while(l < r) {
int mid = l + (r - l) / 2;
ll now = qry(1, 1, H, mid, mid);
if(now >= val) l = mid+1;
else r = mid;
}
return l;
};
ll ans = 0;
sort(v.begin(), v.end());
for(auto [h, k] : v) {
ll now = qry(1, 1, H, h-k+1, h);
ll last = qry(1, 1, H, h-k+1, h-k+1);
ans += now;
int f = first_val(last+1, 1, h-k+1);
int s = first_val(last, h-k+1, h);
upd(1, 1, H, s, h);
upd(1, 1, H, f, f + k - (h - s + 1) - 1);
}
cout << ans;
return 0;
}
