#include "bits/stdc++.h"
using namespace std;
using ll = long long;
#define int ll
using pint = pair<int,int>;
using Graph = vector<vector<int>>;
void YN(bool flg) {cout<<(flg?"YES":"NO")<<'\n';}
void Yn(bool flg) {cout<<(flg?"Yes":"No")<<'\n';}
void yn(bool flg) {cout<<(flg?"yes":"no")<<'\n';}
#define SORT(a) sort(a.begin(),a.end())
#define REVERSE(a) reverse(a.begin(),a.end())
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define out(n) cout << n << '\n'
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<bool> VB;
typedef vector<VI> VVI;
const int MOD = 1000000007;
const long long INF = 1e10; //10^10
const double PI = acos(-1.0L);
const int dx[4] = {1, 0, -1, 0} , dy[4] = {0, 1, 0, -1};
/*mod逆元*/long long modinv(long long a, long long m) {long long b = m, u = 1, v = 0;while (b) {long long t = a / b;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;}
template< typename T >T mod_pow(T x, T n, T p=MOD) {T ret = 1;while(n > 0) {if(n & 1) (ret *= x) %= p;(x *= x) %= p;n >>= 1;}return ret;}
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T>auto MAX(const T& a) { return *max_element(a.begin(),a.end()); }
template<class T>auto MIN(const T& a) { return *min_element(a.begin(),a.end()); }
template<class T, class U>U SUM(const T& a, const U& v) { return accumulate(a.begin(),a.end(), v); }
template<class T, class U>U COUNT(const T& a, const U& v) { return count(a.begin(),a.end(), v); }
template<class T, class U>int LOWER(const T& a, const U& v) { return lower_bound(a.begin(),a.end(), v) - a.begin(); }
template<class T, class U>int UPPER(const T& a, const U& v) { return upper_bound(a.begin(),a.end(), v) - a.begin(); }
int GCD(int a, int b) { return b ? GCD(b, a%b) : a; }
int LCM(int a, int b) { int g = GCD(a, b); return a / g * b; }
int POW(int a, int n) { int r = 1; while (n > 0) { if (n & 1)r *= a; a *= a; n >>= 1; }return r; }
int isPrime(int n){if(n<2){return 0;}for(int i=2; i*i<=n; i++){if(n%i==0){return 0;}}return 1;}
/*素因数分解*/map< int, int >prime_factor(int n){map< int, int > ret;for(int i = 2; i * i <= n; i++) {while(n % i == 0) {ret[i]++;n /= i;}}if(n != 1) ret[n] = 1;return ret;}
/*約数列挙*/vector<int> divisor(int n){vector<int> v; for(int i=1; i*i<=n; i++){if(n%i==0){v.push_back(i);if(i!=n/i){v.push_back(n/i);}}}sort(v.begin(),v.end()); return v;}

//----------------ライブラリとか----------------

signed main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout<<fixed<<setprecision(15);

    int n; cin >> n;
    VI s(n),t(n); REP(i,n) cin >> s[i] >> t[i];

    vector<pair<int,int>> itv(n); //仕事をソートするための配列
    REP(i,n){
        itv[i].first = s[i] + t[i];
        itv[i].second = s[i] - t[i];
    }
    SORT(itv);
    // REP(i,n){
    //     out(itv[i].first);
    //     out(itv[i].second);
    //     out("------");
    // }

    int ans = 0;
    int et = -INF; //最後に選んだ仕事の終了時間
    REP(i,n){
        if(et<=itv[i].second){
            ans++;
            et = itv[i].first;
        }
    }
    out(ans);

    return 0;
}

Measured memory_bytes: 3456