#include <bits/stdc++.h>
using namespace std;
inline int readint() {
int x = 0;
char ch = getchar_unlocked();
while (ch < '0' || ch > '9')
ch = getchar_unlocked();
while (ch >= '0' && ch <= '9') {
x = x * 10 + ch - '0';
ch = getchar_unlocked();
}
return x;
}
int main() {
int n;
cin >> n;
pair<int, int> origin[n];
int pmax[n], smax[n];
for (int x = 0; x < n; x++) {
origin[x].first = readint(); origin[x].second = readint();
}
int carry = -INT_MAX;
for (int x = 0; x < n; x++) {
pmax[x] = carry;
carry = max(carry, origin[x].first + origin[x].second);
}
carry = -INT_MAX;
for (int x = n - 1; x > -1; x--) {
smax[x] = carry;
carry = max(carry, origin[x].second - origin[x].first);
}
int ans = 0;
for (int x = 0; x < n; x++) {
if (origin[x].first + origin[x].second > pmax[x] &&
origin[x].second - origin[x].first > smax[x]) {
ans++;
}
}
cout << ans;
}
