#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define int long long
#define pint pair<int, int>
#define vint vector<int>
const int mod = 1e9 + 7;
const int shrek = 5e5 + 5;
const int say = INT_MAX / 2;
const int gex = INT_MIN / 2;
const long long oo = 1e18;
bool cmp(pint a, pint b) {
if((a.ss - a.ff) == (b.ss - b.ff)) {
return a.ff > b.ff;
}
return (a.ss - a.ff) > (b.ss - b.ff);
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
pint a[n];
for(int i = 0; i < n; i++) {
cin >> a[i].ff >> a[i].ss;
}
sort(a, a + n, cmp);
int maxi = a[0].ss + a[0].ff;
int ans = 1;
for(int i = 1; i < n; i++) {
if((a[i].ss - a[i].ff) != (a[i - 1].ss - a[i - 1].ff)) {
if(maxi < (a[i].ss + a[i].ff)) {
ans++;
}
}
maxi = max(maxi, a[i].ss + a[i].ff);
}
cout << ans << '\n';
return 0;
}
