#include <bits/stdc++.h>
#define fast ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
#define pb push_back
#define ll long long
#define F first
#define S second
using namespace std;
const int N = 1e7 + 5, MOD = 1e9 + 7;
inline int readInt() {
int x = 0;
char ch = getchar();
while (ch < '0' || ch > '9') ch = getchar_unlocked();
while (ch >= '0' && ch <= '9'){
x = (x << 3) + (x << 1) + ch - '0';
ch = getchar_unlocked();
}
return x;
}
void solve(){
int n = readInt();
pair<int, int> a[n];
for(int i = 0; i < n; ++i){
a[i].F = readInt();
a[i].S = readInt();
}
sort(a, a + n);
int pre_max[n], suf_mn[n + 1];
pre_max[0] = a[0].F + a[0].S;
for(int i = 1; i < n; ++i)
pre_max[i] = max(pre_max[i - 1], a[i].F + a[i].S);
suf_mn[n - 1] = a[n - 1].F - a[n - 1].S;
for(int i = n - 2; i >= 0; --i)
suf_mn[i] = min(suf_mn[i + 1], a[i].F - a[i].S);
int ans = (suf_mn[1] > (a[0].F - a[0].S));
suf_mn[n] = INT_MAX;
for(int i = 1; i < n; ++i){
if((pre_max[i - 1] >= (a[i].F + a[i].S)) or (suf_mn[i + 1] <= (a[i].F - a[i].S)))
continue;
++ans;
}
cout << ans << '\n';
}
int main(){
fast;
int t = 1;
// cin >> t;
while(t--)
solve();
}
