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#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <set>
#include <map>
#include <array>
#include <random>
#include <cmath>
#include <list>
#include <ctime>
#include <sstream>
#include <queue>
#include <climits>
#include <stack>
#include <random>
#include <bitset>
#include <numeric>
#include <cassert>
using namespace std;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;
#define rep(x, b, e) for(int x=(b); x<(e); ++x)
#define trav(a, x) for(auto& a : x)
#define ford(x, b, e) for(int x=((int)(b))-1; x>=(e); --x)
#define all(c) c.begin(),c.end()
#define sz(x) ((int)((x).size()))
#define pb push_back
#define st first
#define nd second
#define mp(x,y) make_pair(x,y)
typedef short int sint;

#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

int P;

bool inMask(int mask, int v) {
	return (mask & (1 << v)) > 0;
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	int n;
	scanf("%d", &n);
	vector<ll> a(n), r(n);
	rep(i, 0, n) {
		scanf("%lld %lld", &a[i], &r[i]);
	}
	set<int> possible;
	rep(mask, 0, (1 << n)) {
		queue<int> toBlow;
		int blown = mask;
		rep(i, 0, n) {
			if ((mask & (1 << i))) {
				toBlow.push(i);
			}
		}
		while (!toBlow.empty()) {
			int cur = toBlow.front(); toBlow.pop();
			rep(i, 0, n) {
				if (inMask(blown, i)) {
					continue;
				}
				if (a[cur] - r[cur] <= a[i] && a[i] <= a[cur] + r[cur]) {
					blown |= (1 << i);
					toBlow.push(i);
				}
			}
		}
		possible.insert(blown);
	}
	printf("%d\n", sz(possible));
}