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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define mp make_pair
#define pb push_back
#define pf push_front
#define eb emplace_back
#define st first
#define nd second
#define vt vector
#define DEBUG if(1)
#define VAR(__var)  #__var << ": " << __var << " "
#define PARA(__var) #__var << ": " << __var.first << ", " << __var.second << " " 
#define FOR(__var, __start, __end)  for(int __var=__start; __var<__end; ++__var)
#define FORB(__var, __start, __end) for(int __var=__start; __var>__end; --__var)
#define all(__var)    (__var).begin(),(__var).end()
#define rall(__var)   (__var).rbegin(),(__var).rend()
#define sz(__var)     (int)(__var).size()
#define satori(__var) int __var; cin>>__var; while(__var--)

using namespace std;

using namespace __gnu_pbds;
template <typename T>
using ord_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

const int INF = 1e9+2137;

int32_t main()
{
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 	
	int n;
	cin >> n;
	
	vt<int> pos(n);
	vt<int> zas(n);
	FOR(i, 0, n)
		cin >> pos[i] >> zas[i];
		
	ll res = 0;
	for(ll mask = 0; mask < (1<<n); ++mask)
	{
		bool kul = 1;
		for(int k=0; k<n; ++k)
		{
			if(mask & (1<<k))
			{
				int x = pos[k]-zas[k];
				auto it = lower_bound(all(pos), x);
				int l = it-pos.begin();
				FOR(j, l, n)
				{	
					if(abs(pos[k]-pos[j]) > zas[k])
						break;
					if(!(mask & (1<<j)))
						kul = 0;
					if(!kul)
						break;
				}	
				if(!kul)
					break;
			}
		}
		if(kul)
			++res;
	}
	
	cout << res << '\n';
	
	return 0;
}