#include "bits/stdc++.h"
#define IOS ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long
#define ull unsigned long long
#define OPEN freopen ("a.in", "r", stdin); freopen ("a.out", "w", stdout);
#define pc __builtin_popcount
#define db double
#define pii pair<int, int>
#define fi first
#define se second
#define F(i,x,y) for (int i = (x); i <= (y); ++i)
#define D(i,x,y) for (int i = (x); i >= (y); --i)
#define lttm iterator
#define fp iterator

using namespace std;

const ll inf = 1ll * 1e18;
//const ll mod = 998244353ll;

const ll mod = 1ll * 1e9 + 7ll;

inline void Rd(int& x) {
	int f = 1;
	x = 0;
	char c = getchar();
	while (c < '0' || c > '9') {
		if (c == '-') f = -1;
		c = getchar();
	}
	while (c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c - 48), c = getchar();
	x *= f;
}

inline void Wt(int x) {
	if (x < 10) {
		putchar(x + 48);
		return;
	}
	Wt(x / 10);
	putchar((x % 10) + 48);
}

int n;

struct Node {
	ll x, p, d;
	ll mn, mx;
}t[140000];

ll sl[310000], sr[310000];
ll ql[310000], qr[310000];

ll ans = inf;

int main() {
//	OPEN
	cin >> n;
	
	F(i, 1, n) cin >> t[i].x >> t[i].p >> t[i].d;
	
	F(i, 1, n) sl[i] = sl[i - 1] + (t[i].d == -1);
	D(i, n, 1) sr[i] = sr[i + 1] + (t[i].d == 1);
	ql[0] = ql[1] = 1;
	F(i, 2, n) {
		ql[i] = ql[i - 1] & (t[i].x <= (t[i - 1].x + t[i - 1].p));
	}
	qr[n] = qr[n + 1] = 1;
	D(i, n - 1, 1) {
		qr[i] = qr[i + 1] & (t[i].x >= (t[i + 1].x - t[i + 1].p));
	}
	
	F(i, 1, n + 1) {
		//cerr<<i<<':'<<ql[i-1]<<' '<<qr[i]<<'\n';
		if (ql[i - 1] && qr[i] && ((t[i - 1].p + t[i - 1].x) >= (t[i].x - t[i].p))) {
			ans = min(ans, 1ll * (sl[i - 1] + sr[i]));
		}
	}
	if (ans == inf) cout << -1;
	else cout << ans;
}