#include<bits/stdc++.h>
#define x first
#define y second
#define pb push_back
#define all(a) (a).begin(), (a).end()
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int maxn = 5e5 + 5;
int n, pot = 1;
int x[maxn];
int e[maxn];
int T1[maxn * 4], T2[maxn * 4];
map<int, int> pos;
vector<ii> v;
void update1(int x, int v) {
x += pot;
T1[x] = min(T1[x], v);
x >>= 1;
while(x > 0)
T1[x] = min(T1[x * 2], T1[x * 2 + 1]), x >>= 1;
}
void update2(int x, int v) {
x += pot;
T2[x] = max(T2[x], v);
x >>= 1;
while(x > 0)
T2[x] = max(T2[x * 2], T2[x * 2 + 1]), x >>= 1;
}
int query1(int x, int lo, int hi, int a, int b) {
if(hi < a || b < lo) return 2e9 + 1;
if(a <= lo && hi <= b) return T1[x];
int mid = (lo + hi) / 2;
int L = query1(x * 2, lo, mid, a, b);
int R = query1(x * 2 + 1, mid + 1, hi, a, b);
return min(L, R);
}
int query2(int x, int lo, int hi, int a, int b) {
if(hi < a || b < lo) return -2e9 - 1;
if(a <= lo && hi <= b) return T2[x];
int mid = (lo + hi) / 2;
int L = query2(x * 2, lo, mid, a, b);
int R = query2(x * 2 + 1, mid + 1, hi, a, b);
return max(L, R);
}
int check(int i, int j) {
return abs(x[i] - x[j]) <= e[i] - e[j];
}
int main() {
scanf("%d", &n);
for(int i = 0;i < n;i++)
scanf("%d%d", x + i, e + i);
while(pot < n) pot <<= 1;
for(int i = 1;i < (pot << 1);i++)
T1[i] = 2e9 + 1, T2[i] = -2e9 - 1;
for(int i = 0;i < n;i++)
v.pb({e[i], x[i]});
sort(all(v));
reverse(all(v));
set<int> s;
for(int i = 0;i < n;i++)
s.insert(x[i]);
vector<int> v1(all(s));
int m = (int)v1.size();
for(int i = 0;i < m;i++)
pos[v1[i]] = i;
int ans = 0;
for(ii p : v) {
int flag = 1;
int A = query1(1, 0, pot - 1, pos[p.y], m - 1);
int B = query2(1, 0, pot - 1, 0, pos[p.y]);
if(p.y - p.x >= A) flag = 0;
if(p.y + p.x <= B) flag = 0;
ans += flag;
if(flag) {
update1(pos[p.y], p.y - p.x);
update2(pos[p.y], p.y + p.x);
}
}
printf("%d\n", ans);
return 0;
}
