#include <bits/stdc++.h>
using namespace std;
const int N = 500005;
const long long oo = 1e18;
int n;
array<int, 3> a[N], b[N];
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, i}; b[i] = {x, x - e, i};
}
sort(a + 1, a + 1 + n, [&] (const array<int, 3> &X, const array<int, 3> &Y) {
return X[0] < Y[0] || (X[0] == Y[0] && (X[1] > Y[1] || (X[1] == Y[1] && X[2] < Y[2])));
});
sort(b + 1, b + 1 + n, [&] (const array<int, 3> &X, const array<int, 3> &Y) {
return X[0] < Y[0] || (X[0] == Y[0] && (X[1] > Y[1] || (X[1] == Y[1] && X[2] < Y[2])));
});
for (int i = n; i; i--) {
if (idas.empty() || a[i][1] ^ a[idas.back()][1] || a[i][0] ^ a[idas.back()][0]) {
while (!idas.empty() && (a[i][1] >= a[idas.back()][1] || (a[i][1] == a[idas.back()][1] && a[i][0] ^ a[idas.back()][0]))) idas.pop_back();
idas.emplace_back(i);
}
}
reverse(begin(idas), end(idas));
for (int i = 1; i <= n; i++) {
while (!idbs.empty() && b[i][1] <= b[idbs.back()][1]) 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][0] < b[i2][0]) i++;
else if (a[i1][0] > b[i2][0]) j++;
else {
ans += (a[i1][2] == b[i2][2]);
i++;
j++;
}
}
cout << ans;
}
signed main(void) {
ios::sync_with_stdio(false); cin.tie(nullptr);
solve();
return 0;
}
