#include <bits/stdc++.h>
#define REP(i, l, r) for (int i = (l); i <= (r); ++ i)
#define DEP(i, r, l) for (int i = (r); i >= (l); -- i)
#define fi first
#define se second
#define pb emplace_back
#define mems(x, v) memset((x), (v), sizeof(x))
using namespace std;
namespace Milkcat {
	typedef long long LL;
	typedef pair<LL, LL> pii;
	const int N = 1e6 + 5;
	LL n, rs, a[N], p[N], d[N], pr[N], sf[N];
	int main() {
		cin >> n;
		REP(i, 1, n) cin >> a[i] >> p[i] >> d[i];
		pr[0] = sf[n + 1] = 0, rs = 1e18;
		REP(i, 1, n) {
			pr[i] = pr[i - 1] + (d[i] < 0);
			if (i > 1 && a[i] - a[i - 1] > p[i - 1]) pr[i] = 1e18;
		}
		DEP(i, n, 1) {
			sf[i] = sf[i + 1] + (d[i] > 0);
			if (i < n && a[i + 1] - a[i] > p[i + 1]) sf[i] = 1e18;
		}
		REP(i, 1, n + 1)
			if (p[i - 1] + p[i] >= a[i] - a[i - 1]) rs = min(rs, pr[i - 1] + sf[i]);
		cout << (rs > 1e9 ? -1 : rs) << '\n';
		return 0;
	}
}
int main() {
//	freopen("a.in", "r", stdin);
//	freopen("a.out", "w", stdout);
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	int T = 1;
	while (T --) Milkcat::main();
	return 0;
}