#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
using u128 = unsigned __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n;
    std::cin >> n;
    
    std::vector<int> x(n), p(n), d(n);
    for (int i = 0; i < n; i++) {
        std::cin >> x[i] >> p[i] >> d[i];
    }
    
    int ans = n + 1;
    
    int cost = std::count(d.begin(), d.end(), 1);
    int bad = 0;
    for (int i = 1; i < n; i++) {
        bad += (p[i] < x[i] - x[i - 1]);
    }
    for (int i = 0; i < n - 1; i++) {
        if (d[i] == 1) {
            cost--;
        } else {
            cost++;
        }
        bad -= (p[i + 1] < x[i + 1] - x[i]);
        if (bad == 0 && p[i] + p[i + 1] >= x[i + 1] - x[i]) {
            ans = std::min(ans, cost);
        }
        bad += (p[i] < x[i + 1] - x[i]);
    }
    
    if (ans > n) {
        ans = -1;
    }
    std::cout << ans << "\n";
    
    return 0;
}