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#include "bits/stdc++.h"
using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
template<class T> int size(T &&x) {
	return int(x.size());
}
template<class A, class B> ostream& operator<<(ostream &out, const pair<A, B> &p) {
	return out << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &out, T &&x) -> decltype(x.begin(), out) {
	out << '{';
	for(auto it = x.begin(); it != x.end(); ++it)
		out << *it << (it == prev(x.end()) ? "" : ", ");
	return out << '}';
}
void dump() {}
template<class T, class... Args> void dump(T &&x, Args... args) {
	cerr << x << ";  ";
	dump(args...);
}
#ifdef DEBUG
  struct Nl{~Nl(){cerr << '\n';}};
# define debug(x...) cerr << (strcmp(#x, "") ? #x ":  " : ""), dump(x), Nl(), cerr << ""
#else
# define debug(...) 0 && cerr
#endif
mt19937_64 rng(0);
int rd(int l, int r) {
	return uniform_int_distribution<int>(l, r)(rng);
}
// end of templates

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n; cin >> n;
	vector<pair<LL, LL>> vec(n);
	for(auto &[a, r]: vec) cin >> a >> r;

	vector<LL> blown(n);
	REP(i, n) {
		blown[i] = (1LL << i);
		LL lb = vec[i].first - vec[i].second, rb = vec[i].first + vec[i].second;
		for(int j = i-1; j >= 0; --j) {
			if(vec[j].first < lb) break;
			blown[i] += (1LL << j);
			lb = min(lb, vec[j].first - vec[j].second);
		}
		FOR(j, i+1, n-1) {
			if(rb < vec[j].first) break;
			blown[i] += (1LL << j);
			rb = max(rb, vec[j].first + vec[j].second);
		}
	}
	debug(blown);

	map<LL, bool> mmap;
	LL ans = 0;
	REP(msk, (1 << n)) {
		int temp = 0;
		REP(i, n)
			if((msk >> i) & 1)
				temp |= blown[i];
		ans += (mmap.find(temp) == mmap.end());
		mmap[temp] = true;
	}

	cout << ans << '\n';
}