#include<iostream>
#include<stdio.h>
#include<stdint.h>
#include<vector>
#include<algorithm>
#include<utility>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<iomanip>
#include<string>
#include<math.h>
#include<assert.h>
using namespace std;
const double PI = (double) atan(1.0) * 4;
const int64_t INF = (int64_t) 1e18 + 777;
const int64_t mINF = (int64_t) 2e9 + 777;
const int64_t offset = (int64_t) 1e6 + 777;
const int64_t MOD = 1e9 + 7;
const int nbit = 11;
const int ndig = 10;
const int nchar = 26;
const int p1 = 31;
const int p2 = 53;
const int D = 4;
int dr[D] = {0, 1, 0, -1};
int dc[D] = {1, 0, -1, 0};
// 0 right // 1 down // 2 left // 3 up
int modadd(int t1, int t2)
{
int res = t1 + t2;
if(res >= MOD) res -= MOD;
return res;
}
int modmul(int t1, int t2)
{
int64_t res = 1LL * t1 * t2;
return (res % MOD);
}
struct House
{
int x; int e;
House(int x_, int e_) : x(x_), e(e_) {}
bool operator < (const House& o) const
{
if(x == o.x) return e < o.e;
return x < o.x;
}
};
struct Solution
{
int n;
vector<House> a;
Solution() {}
void solve()
{
cin >> n;
set<pair<int, int> > st;
for(int i = 0; i < n; i++)
{
int x; int e;
cin >> x >> e;
if(!st.count(make_pair(x, e))) a.emplace_back(x, e);
st.insert(make_pair(x, e));
}
n = a.size();
sort(a.begin(), a.end());
vector<bool> give(n, true);
int max_ = -mINF;
for(int i = 0; i < n; i++)
{
if(a[i].x + a[i].e <= max_) give[i] = false;
max_ = max(max_, a[i].x + a[i].e);
}
max_ = -mINF;
for(int i = n - 1; i >= 0; i--)
{
if(-a[i].x + a[i].e <= max_) give[i] = false;
max_ = max(max_, -a[i].x + a[i].e);
}
int ans = 0;
for(int i = 0; i < n; i++)
{
ans += give[i];
}
cout << ans << "\n";
}
int modsub(int t1, int t2)
{
int res = t1 - t2;
if(res < 0) res += MOD;
return res;
}
bool BIT(int& mask, int& j)
{
return (mask & MASK(j));
}
int64_t Abs(int64_t t1)
{
if(t1 < 0) return -t1;
return t1;
}
int MASK(int j)
{
return (1 << j);
}
};
void __startup()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
}
int main()
{
__startup();
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
Solution().solve();
}
return 0;
}
