#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define ent "\n"
const int maxn = 1e7 + 100;
const ll INF = (ll)1e18 + 100;
const int inf = 1e9 + 100;
const int MOD = 1e9 + 7;
const int maxl = 30;
const int P = 31;
int n;
int a[maxn];
int b[maxn];
bool ok[maxn];
void test(){
cin >> n;
int mx = -inf;
for(int i = 1; i <= n; i++){
cin >> a[i] >> b[i];
if(a[i] + b[i] > mx){
ok[i] = 1; }
mx = max(mx, a[i] + b[i]);
}
int mn = inf * 2, cnt = 0;
for(int i = n; i > 0; i--){
if(a[i] - b[i] < mn && ok[i]) cnt++;
mn = min(mn, a[i] - b[i]);
}
cout << cnt;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int t = 1; t = 1;
while(t--) test();
cout << ent;
}
