/* Do what u love, love what u do */
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define rsz resize
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define f first
#define s second
#define mp make_pair
#define For(i, l, r) for (int i = l; i < r; i++)
#define ForE(i, l, r) for (int i = l; i <= r; i++)
#define Ford(i, r, l) for (int i = r; i > l; i--)
#define FordE(i, r, l) for (int i = r; i >= l; i--)
#define Fora(i, a) for (auto i : a)
long double pi = 3.14159265359;
stack<pair<ll,ll>> st;
ll readint () {
bool minus = false;
ll result = 0;
char ch;
ch = getchar();
while (true) {
if (ch == '-') break;
if (ch >= '0' && ch <= '9') break;
ch = getchar();
}
if (ch == '-') minus = true; else result = ch-'0';
while (true) {
ch = getchar();
if (ch < '0' || ch > '9') break;
result = result*10 + (ch - '0');
}
if (minus)
return -result;
else
return result;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll n = readint();
ForE(i,1,n){
bool ok = true;
ll x = readint();
ll y = readint();
while(!st.empty()){
auto t = st.top();
if (x+y<=t.f+t.s){
ok = false;
break;
}
if (x-y<=t.f-t.s){
st.pop();
}
else {
break;
}
}
if (ok){
st.push(mp(x,y));
}
}
cout << st.size();
}
