This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#define Magic ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define tsts int t; cin >> t; while(t--)
#include <bits/stdc++.h>
using namespace std;
using lli = long long int;
using ull = unsigned long long int;
using ld = long double;
using str = string;
#define pb push_back
#define pf push_front
#define sz size()
#define bg begin()
#define ers erase
inline void debugMode() {
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    #endif // ONLINE_JUDGE
}
const lli N = 1e3 + 100;
vector <lli> a[N], b[N];
lli visited[N], ans;
void dfs(lli x){
	visited[x] = 1;
	if (b[x].sz == 0)
		ans++;
	for (auto it : b[x]){
		if (!visited[it])
			dfs(it);
	}
}
int main(){
    Magic
    //debugMode();
    lli n;
    cin >> n;
    lli x[n], e[n];
    map <pair <lli, lli>, lli> cnt;
    for (lli i = 0 ; i < n ; i++){
    	cin >> x[i] >> e[i];
    	cnt[{x[i], e[i]}]++;
    }
    for (auto it : cnt){
    	ans+=it.second - 1;
    }
    for (lli i = 0 ; i < n ; i++){
    	for (lli j = 0 ; j < n ; j++){
    		if (i == j)
    			continue ;
    		if (abs(x[i] - x[j]) <= e[i] - e[j]){
    			a[i].pb(j);
    			b[j].pb(i);
    		}
    	}
    }
    for (lli i = 0 ; i < n ; i++){
    	if (!visited[i])
    		dfs(i);
    }
    cout << ans;
}
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⠤⢲⣦⡀⠀⣠⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣀⣀⣠⠖⠚⠓⠒⠒⠲⠿⣍⣛⣻⣦⣷⢠⣻⣀⠤⠤⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⠔⡿⠓⠲⠬⢥⡤⠤⠤⠤⠤⣤⣀⣀⣈⣻⣿⣿⠓⠉⣀⡤⠔⢶⣻⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣤⢤⠞⠁⣼⠀⠀⠀⠀⠀⠀⠰⠶⢌⣽⡶⠟⢏⡁⢈⣉⣭⣷⡯⣝⠒⢦⣄⠙⠷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡾⣵⠿⣳⡟⠉⠉⠿⠀⠀⡀⠀⠀⣀⣀⣢⣾⣿⡚⠓⠒⠒⠒⠻⢿⣟⣧⡀⢠⣢⡻⠙⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⡀⢿⣟⣲⢿⣷⢀⣤⣠⣄⣈⢿⣷⣤⣷⣻⡓⠒⠻⠭⢷⡄⠒⠲⢶⣦⣬⣻⣏⢦⡈⢿⣆⠘⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⢖⣩⠷⢎⣙⣿⣿⣼⡼⣿⣟⣽⣻⢯⢿⠞⣌⠙⢳⡕⠀⠙⠲⣶⠤⢄⡠⣄⡈⠛⣿⣿⣧⢳⣌⢻⡆⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠰⠗⠉⢀⣾⠟⠒⡿⣫⡿⡾⢫⢟⡏⠉⢸⡀⠑⢾⡆⢤⣻⣶⣤⣘⣲⣿⣶⡽⠿⣯⠲⣌⣇⢹⣷⣿⣆⠸⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠀⠀⡼⠀⣿⢣⣧⠋⣸⠀⣰⢀⣿⣆⠀⠰⣄⠙⣧⣨⣿⣿⣿⣯⣿⣦⠘⣷⡌⢻⡄⠿⣆⠟⣆⢇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⠀⠀⠀⠀⠀⠀⠀⠀⡇⡼⣹⠈⢣⠆⡇⣰⣻⣼⣿⣽⣷⣦⣹⣿⣟⣯⠉⠘⣿⠏⠃⠀⣷⣽⡿⣾⡹⣷⣹⣧⡈⢺⡀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⢾⠟⠉⠀⠀⠀⠀⠀⠀⠀⠀⣷⣱⣽⡀⢸⣆⢳⣿⣇⣷⡿⠖⠿⠷⢦⣙⣆⠩⡗⠀⠀⠀⠀⠀⡯⠿⠳⣟⠻⣽⣄⢧⠈⠳⣷⡀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⣸⡇⡏⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣤⣿⣿⣷⣸⣿⡀⣿⣅⠛⠇⠀⠀⠀⠀⢈⠙⠂⠀⠀⠀⠀⠀⣸⣿⠀⢠⣜⢦⠘⢿⣮⣷⡀⠀⠙⢦⡀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⢯⣇⠙⢄⣀⠀⠀⠀⢀⣀⡠⣴⣾⣫⠵⠛⣿⣻⠿⣷⣹⣾⣷⡠⡀⠀⠀⠀⠻⠦⠀⣀⠔⠀⠀⣴⣿⣸⣧⡀⠳⣝⠳⢴⡙⢞⣏⠢⡀⠀⠹⡄⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⢀⣀⣀⣈⣻⣤⣀⠈⠉⠻⠿⢿⣺⣿⡵⣶⢶⣦⠀⠘⣿⢷⣾⢿⣿⡋⢙⣮⣄⡀⠀⠀⠉⠈⠀⠀⢀⢞⣿⣼⣿⣿⣿⣆⡀⠙⢦⣝⣮⠛⢷⡙⢆⠀⣷⠀⠀⠀⠀
///⠀⠀⠀⢠⡴⢟⣫⠤⠖⠒⠛⢛⣲⣿⣿⣿⠟⠋⢱⣿⣴⣷⣿⣹⢃⣀⣘⠃⢩⢿⣫⣥⣿⠧⢿⣿⣗⡶⣤⣄⣀⣴⣷⣻⣿⣿⠻⠘⣏⠛⢿⣦⣀⠱⢤⣉⡑⠛⠮⢿⣹⠀⠀⠀⠀
///⠀⢠⢖⠵⠊⠁⢀⡤⠖⣲⣿⣿⣟⣻⣿⣋⠀⠀⠈⢿⣿⡿⠟⣵⣿⣿⣿⣷⡏⠈⢿⡿⣷⣤⣼⢿⣿⣿⢶⣯⣭⣵⣾⢿⣿⠿⢦⡀⢹⠀⠈⣏⠉⠉⢻⣶⣯⡑⠦⣄⠈⠳⣄⠀
///⠀⠹⠁⠀⠀⣞⢁⡾⢽⣯⣝⣛⣛⣯⣭⣽⣿⣷⣶⣤⣤⣴⣿⣿⣿⣿⣿⣿⡀⣀⣼⣀⠈⠙⠛⠷⣾⡿⢿⡟⣿⠟⠁⣈⣥⡴⠾⠷⢾⡄⠀⣿⠀⠀⠈⢇⠘⣿⣤⣀⠑⢦⡘⢧⠀
///⠄⠀⠀⠀⠀⠈⠻⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⢿⡿⠛⣻⢏⡽⣯⡄⠘⣏⣿⡏⠈⠙⠓⠶⣤⣀⠀⠙⢿⣿⡇⢀⡿⠋⠁⠀⢀⣀⣸⡇⠀⣟⣀⠀⠀⠀⠙⠃⣿⡎⠑⣤⡙⣌⡇
///⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⡥⣖⡯⠖⢋⣡⡞⣼⣿⠀⠀⢹⣿⣷⠀⠀⣀⡀⠀⠉⠻⣦⠀⢿⣿⡿⠁⣠⡶⠟⠋⠉⠹⣆⣸⣿⣿⠀⣀⡤⣤⡀⣿⠇⠀⢸⠳⡜⡇
///⠀⠀⠀⠀⠀⠀⠀⠀⣈⣿⣿⣿⣿⣿⣿⣏⢿⣗⠒⠊⠉⢸⠁⡿⡏⠀⢀⣿⡿⣁⠤⢶⣿⣽⡆⠀⠀⠘⢷⡈⠉⣡⠾⠋⠀⠀⣠⣆⢠⣿⣿⣿⡟⢀⣷⠒⢺⣧⡏⠀⠀⢸⠀⢹⣹
///⠀⠀⠀⠀⠀⠀⡠⢪⠟⡽⠙⢶⣾⣿⣿⣿⣷⡻⣦⡀⠀⠀⢣⣇⡇⢀⡞⣸⠏⠁⠀⠀⡇⢻⡀⠀⠀⣾⣶⡟⣿⣥⡄⠀⠀⢠⣇⣼⡶⣿⣿⠋⣸⣾⣷⣚⣽⡟⠀⠀⠀⣏⠀⡼⣿
///⠀⠀⠀⠀⢀⠎⡴⣣⣾⠟⣡⠞⢹⡿⣿⢿⣿⣿⣿⣷⣄⠀⠈⠻⡹⣼⠀⣿⡄⠀⠀⠀⠉⠻⣷⡀⠀⠙⠿⠇⣿⠿⠇⠀⠀⢠⡿⠋⢇⢹⣟⢷⠫⣿⣟⡿⠋⠀⠀⣠⣾⢞⡜⠁⡿
///⠀⠀⠀⠀⡼⡼⣵⠏⡏⣰⠃⠀⢾⡇⠈⠻⣿⣮⡉⠹⣿⣧⣄⡀⠙⣇⠀⠸⣿⣄⡀⠀⠀⠀⠈⢉⣧⡴⠀⠠⡄⣀⡤⠤⠴⠋⠁⠀⠈⢻⣿⣾⣤⡿⠋⠀⠀⠀⣉⣽⠿⠋⠀⣰⠃
///⠀⠀⠀⠀⣿⣽⠋⠀⡇⡇⠀⠀⠘⣷⢠⣶⢮⣻⣿⣦⠈⠛⠙⠹⣷⠘⢦⣤⣿⣳⣭⣑⣒⣒⣺⣿⢿⣀⣀⣀⣿⣧⣀⣀⣀⡤⠴⠒⣶⣿⣏⣾⡿⠁⠀⠀⠀⠉⠉⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⢻⡏⠀⠀⢳⣇⠀⠀⠀⠈⠈⣿⣾⣿⣿⣮⣿⣦⠀⠀⢿⣶⡫⣿⣿⣿⣿⣿⡹⣯⣊⠁⠉⠉⠉⠉⢙⣮⣷⣶⡤⣤⣶⣿⣿⣟⣾⢿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠸⣿⣦⡀⠀⠙⠦⠀⠀⢀⣼⠿⣽⣿⣯⣷⣼⡷⢾⣻⣾⣿⠞⢿⢻⡷⠻⣿⣏⡙⢝⣻⡾⡖⠒⣻⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡟⣎⠣⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠈⠁⠀⠀⠀⠀⣴⣋⣉⣩⣿⣿⢿⣟⣷⣾⣯⡟⢱⡇⠀⠘⣿⠣⡀⣈⣻⣿⣿⣿⣷⣷⣶⣿⣿⣟⠋⡿⣹⣿⣿⣿⣿⢟⣏⠺⠿⠶⠭⠷⠂⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⢰⣿⣿⣿⣿⣿⣿⣿⢹⣮⣾⣿⡿⢋⣶⢸⡇⠀⠀⠈⢷⡑⠈⢻⣟⠛⠛⠿⠋⠙⠓⣭⣿⣹⣵⣿⣿⣿⣿⣿⠈⠻⣷⣄⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠙⢟⣛⡭⠶⢾⡿⠃⠀⠀⢸⢹⣾⣇⠀⠀⠀⠀⠻⣟⣿⡏⠀⠀⠀⠀⢰⣿⣿⢿⡇⣿⣿⣿⣿⣟⡏⠀⠀⠀⠉⠙⠓⠒⠂⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⡟⠀⠀⠀⢰⣿⢸⣿⢿⡀⠀⠀⠀⠀⢸⣿⣣⠀⠀⠀⢠⣿⡟⣷⣾⣿⢿⣿⣿⣿⣿⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣿⠁⠀⠀⠀⠘⡿⡿⢿⣏⣧⠀⠀⠀⢀⣾⣿⠿⠀⢀⣴⣿⣿⢿⡹⡇⣿⠈⣿⣿⡟⣾⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⡇⠀⠀⠀⠀⢳⢧⠈⢿⣿⠀⠀⢀⣼⣿⠕⠁⣠⣾⡿⣻⠏⠀⢹⣹⣿⣆⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣿⣷⠀⠀⠀⠀⠈⣏⢧⠀⢻⣧⠶⣋⠿⠋⣀⣾⣟⣿⠞⠁⠀⠀⠀⢯⣿⣿⣿⣿⣿⡏⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣿⣿⣇⠀⠀⠀⠀⠸⡜⣆⠈⢷⣿⠀⢠⣾⣿⠟⢻⡏⠀⠀⠀⠀⠀⠘⣿⣿⠏⣿⣿⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡻⣿⣿⣦⡀⠀⠀⠀⢧⠘⣆⠈⢷⠒⠛⢻⡿⠄⠘⣧⠀⠀⠀⠀⠀⢰⣷⣹⠀⠙⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣷⣝⣿⣿⣷⣄⠀⠀⠈⢇⠸⡄⠈⣇⠀⠀⢻⣆⠀⠘⣇⠀⠀⣠⣾⣽⢹⡟⠀⢰⣷⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣾⢻⠙⢿⣿⡇⠀⠀⠈⢧⢳⠀⢸⡀⠀⠀⢻⣆⠀⢻⡄⢠⣿⣯⣽⣓⣧⣤⠾⢹⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣼⡇⠀⠙⣿⠀⠀⠀⠈⢏⢧⠀⣇⠀⠀⠀⢻⣆⠀⢷⠘⣿⣮⡻⣿⠁⠀⢀⣯⣿⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢿⣿⣧⡀⠀⠀⠀⠀⠀⠀⠘⡾⡄⢸⠀⠀⠀⠈⢻⣆⠈⢷⣷⣾⣟⣻⣶⣿⡿⠛⢿⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣿⣿⣿⣦⣀⠀⠀⠀⠀⠀⢳⣇⠘⡆⠀⠀⠀⠀⠻⣶⢺⡏⢹⡟⠀⠉⠁⠀⠀⠀⢩⣍⠙⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠸⣟⣿⣿⣿⣧⠀⢀⣤⣤⡸⣸⠀⡇⠀⠀⠀⠀⠀⠙⣿⣷⢡⣿⣶⣄⠀⠀⣄⠀⣦⣍⠙⢳⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠹⡿⢿⡙⠿⠀⢸⡟⢲⣷⡿⡄⢿⠀⠀⠀⠀⠀⠀⠘⣏⢸⣇⣍⢻⣷⣀⢻⣦⣤⣌⡙⣦⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠹⣯⢷⠀⠀⠸⡇⠀⢿⣧⡇⢸⠀⠀⠀⠀⠀⠀⠀⣼⢸⣿⣯⠀⣿⣿⣷⣝⣿⣻⣿⣼⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣎⣧⠀⠐⣇⠀⠘⣽⣿⡸⡆⠀⠀⠀⠀⠀⠀⠈⠋⠈⠻⣼⣿⢶⢿⣿⣯⡻⣿⣿⣾⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⡼⡆⠀⣿⡀⠀⣿⢿⡇⢷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⣿⣾⢧⠈⠙⠿⣮⠟⠉⠙⢦⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢿⢻⢠⣿⡇⠀⠹⣄⢳⣜⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢹⡏⠪⠳⢤⣄⣀⠀⠀⠀⠈⢣⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⣎⣿⡟⡇⠀⠀⠈⢻⣿⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢳⡄⠀⠀⠀⠙⢧⡀⢀⡄⠈⡇⠀⠀⠀⠀⠀⠀⠀⠀
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