Merge Intervals

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static int[] Ria(string line = null)
    {
        line ??= Console.ReadLine();
        if (string.IsNullOrWhiteSpace(line)) return Array.Empty<int>();
        return line.Trim().Split(new[] { ' ', ',', '\t' }, StringSplitOptions.RemoveEmptyEntries)
            .Select(int.Parse).ToArray();
    }
    static string[] Rsa()
    {
        int n = int.Parse(Console.ReadLine());
        var arr = new string[n];
        for (int i = 0; i < n; i++) arr[i] = Console.ReadLine();
        return arr;
    }
    static void W(params object[] parts) => Console.WriteLine(string.Join(" ", parts));
    static void Wb(bool v) => Console.WriteLine(v ? "true" : "false");
    static void Wi(int v) => Console.WriteLine(v);
    static void Ws(string v) => Console.WriteLine(v);

    static void Main()
    {
int n = int.Parse(Console.ReadLine());
var list = new List<int[]>();
for (int i = 0; i < n; i++) list.Add(Ria());
list.Sort((a, b) => a[0].CompareTo(b[0]));
var merged = new List<int[]>();
foreach (var iv in list) {
    if (merged.Count == 0 || merged[^1][1] < iv[0]) merged.Add(iv);
    else merged[^1][1] = Math.Max(merged[^1][1], iv[1]);
}
Wi(merged.Count);
    }
}