#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define uint unsigned int
#define inf (ll)1e18
#define e1 ' '
#define e2 '\n'
#define ld long double
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define pll pair<ll,ll>
#define sf(x) sizeof(x)
#define print_double(d, n) cout<<fixed<<setprecision(n)<<d<<end1;
bool dcmp(int x, int y) {return x > y;}
bool acmp(int x, int y) {return x < y;}
bool afcmp(pair<int, int> a, pair<int, int> b) {return a.first < b.first;}
bool dfcmp(pair<int, int> a, pair<int, int> b) {return a.first > b.first;}
bool ascmp(pair<int, int> a, pair<int, int> b) {return a.second < b.second;}
bool dscmp(pair<int, int> a, pair<int, int> b) {return a.second > b.second;}
int aabs(int a) {return a < 0 ? -a : a;}
ll tmax(ll a, ll b, ll c) {return max(max(a, b), c);}
ll tmin(ll a, ll b, ll c) {return min(min(a, b), c);}
bool in_range(int x, int l, int r) {return x >= l && x <= r;}
bool is_prime(int val) {
if (val == 2) {
return true;
}
if (val % 2 == 0) {
return false;
}
for (int i = 3; i * i <= val; i += 2) {
if (val % i == 0) {
return false;
}
}
return true;
}
int lowbit(int x) {return x & (-x);}
inline ll gcd(ll x, ll y) {return y ? gcd(y, x % y) : x;}
inline ll lcm(ll x, ll y) {return x / gcd(x, y) * y;}
const int maxN = 1e5+5;
const int maxH = 1e5+5;
vector<pair<ll,ll>> s;
ll diff[maxH];
pair<int, int> d[2*maxH]; // (first nonzero )
int H, curH;
pii merge(pii l, pii r){
int lz = l.first == -1?r.first:l.first;
int rz = r.second==-1?l.second:r.second;
return mp(lz, rz);
}
void build(int l, int r, int p) {
if (l == r) { // leaf node
d[p] = mp(-1, -1);
return;
}
int m = l + ((r - l)/2);
build(l, m, 2*p);
build(m + 1, r, 2*p+1);
d[p] = merge(d[2*p],d[2*p+1]);
}
void _update(int idx, bool flag, int l, int r, int p) {
if (l == r) { // the one leaf node we need to update
if(flag){ // zero
d[p] = mp(-1, -1);
}
else{ // nonzero
d[p] = mp(idx,idx);
}
return;
}
int m = l + ((r - l) / 2);
if (idx <= m) {
_update(idx, flag, l, m, 2*p);
}
else {
_update(idx, flag, m + 1, r, 2*p+1);
}
d[p] = merge(d[2* p], d[2*p+1]);
}
int _query_left(int p, int s, int t, int l, int r) {
// [l,r] is the query range
if (s > r || t < l) {
return -1;
}
if (s >= l && t <= r) { // return idx of the rightmost nonzero element in [s,t]
return d[p].second;
}
int mid = s + (t-s)/2;
int right_result = _query_left(2*p + 1, mid + 1, t, l, r);
return right_result==-1?_query_left(2 * p, s, mid, l, r):right_result;
}
int _query_right(int p, int s, int t, int l, int r) {
// [l,r] is the query range
if (s > r || t < l) {
return -1;
}
if (s >= l && t <= r) {
return d[p].first;
}
int mid = s + (t-s)/2;
int left_result = _query_right(2 * p, s, mid, l, r);
return left_result==-1?_query_right(2 * p + 1, mid + 1, t, l, r):left_result;
}
void update(int idx, int x) {
if(idx > H){
return;
}
diff[idx] += x; // Add x to the current value
_update(idx, diff[idx]==0, 1, H, 1);
}
int query_left(int k) {
if(k==1){
return -1;
}
return _query_left(1,1,H,1,k-1);
}
int query_right(int k) {
if(k == curH){
return -1;
}
return _query_right(1,1,H,k+1,curH);
}
void solve() {
int n, h, k;
cin >> n;
for(int i =1;i<=n;++i){
cin >> h >> k;
H = max(H, h);
s.pb(mp(h,k));
}
sort(s.begin(), s.end());
memset(diff, 0, sf(diff));
build(1, H, 1); // this is to prevent curH+1 from overflowing and causing p to refer to the wrong node
update(1, 1);
update(s[0].second + 1,-1);
for(int j = 1; j<n;++j){
// cout << j << e1 << query_right(2) << e2;
h =s[j].first;
k = s[j].second;
curH = h;
if(diff[curH -k +1] != 0){
update(curH+1,-1);
update(curH -k + 1, 1);
}
else{
int A = query_left(curH -k+1);
int B = query_right(curH-k+1);
A++;
// cout << A << e1 << B << endl;
if (B == -1){
B = curH;
}
else{
B--;
}
//cout << A << e1 << B << endl;
update(curH+1,-1);
update(A-1, 1);
update(A+B-curH+k-1, -1);
update(B+1, 1);
}
// for(int i = 1;i<=H;++i){
// cout << diff[i] << e1;
// }
// cout << e2;
}
ll ans = 0;
ll cur = 0;
for(int i = 1;i<=H;++i){
cur += diff[i];
ans += (cur-1)*cur;
}
cout<<ans/2<<endl;
}
void open_file() {
freopen("test.in", "r", stdin);
freopen("test.out", "w", stdout);
}
void prep(){
}
int main(void) {
int t = 1;
// open_file();
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
// cin >> t;
prep();
while (t--) {
solve();
}
return 0;
}
