#include <bits/stdc++.h>
using namespace std;
const int N = 500005;
const long long oo = 1e18;
int n;
pair<int, int> a[N], b[N];
map<pair<int, int>, vector<int>> m1, m2;
vector<int> idas, idbs;
void solve(void) {
cin >> n;
for (int i = 1, x, e; i <= n; i++) {
cin >> x >> e;
a[i] = {x, x + e}; b[i] = {x, x - e};
m1[a[i]].emplace_back(i);
m2[b[i]].emplace_back(i);
}
sort(a + 1, a + 1 + n, [&] (const pair<int, int> &X, const pair<int, int> &Y) {
return X.first < Y.first || (X.first == Y.first && X.second >= Y.second);
});
sort(b + 1, b + 1 + n, [&] (const pair<int, int> &X, const pair<int, int> &Y) {
return X.first < Y.first || (X.first == Y.first && X.second >= Y.second);
});
for (int i = n; i; i--) {
while (!idas.empty() && a[i].second >= a[idas.back()].second) idas.pop_back();
idas.emplace_back(i);
}
reverse(begin(idas), end(idas));
for (int i = 1; i <= n; i++) {
while (!idbs.empty() && b[i].second <= b[idbs.back()].second) idbs.pop_back();
idbs.emplace_back(i);
}
int ans = 0;
for (int i = 0, j = 0; i < (int)idas.size() && j < (int)idbs.size();) {
int i1 = idas[i], i2 = idbs[j];
if (a[i1].first < b[i2].first) i++;
else if (a[i1].first > b[i2].first) j++;
else {
for (int ii = 0, jj = 0; ii < (int)m1[a[i1]].size() && jj < (int)m2[b[i2]].size();) {
int x = m1[a[i1]][ii], y = m2[b[i2]][jj];
if (x < y) ii++;
else if (x > y) jj++;
else {
ans++;
break;
}
}
i++;
j++;
}
}
cout << ans;
}
signed main(void) {
ios::sync_with_stdio(false); cin.tie(nullptr);
solve();
return 0;
}
