Friendless Dr. Sheldon Cooper MST, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

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

namespace Rextester
{
    public class Program
    {
        /*
// Sample code to perform I/O:

name = Console.ReadLine();                  // Reading input from STDIN
Console.WriteLine("Hi, {0}.", name);        // Writing output to STDOUT

// Warning: Printing unwanted or ill-formatted data to output will cause the test cases to fail
*/

// Write your code here
private class Edge {
    public int Src { get; set; }
    public int Dest { get; set; }
}
private class UnionFind {
    private readonly int[] m_parent;
    private readonly int[] m_size;
    public UnionFind(int numVertices) {
        m_parent = new int[numVertices + 1];
        for (var i = 0; i <= numVertices; i++) {
            m_parent[i] = i;
        }
        m_size = new int[numVertices + 1];
    }
    private int FindParent(int node) {
        while (node != m_parent[node]) {
            m_parent[node] = m_parent[m_parent[node]];
            node = m_parent[node];
        }
        return node;
    }
    public bool IsConnected(int u, int v) {
        var uParent = FindParent(u);
        var vParent = FindParent(v);
        return uParent == vParent;
    }
    public void Union (int u, int v) {
        var uParent = FindParent(u);
        var vParent = FindParent(v);
        if (uParent == vParent) {
            return;
        }
        if (m_size[u] < m_size[v]) {
            m_parent[u] = v;
            m_size[v] += m_size[u];
        } else {
            m_parent[v] = u;
            m_size[u] += m_size[v];
        }
    }
}
public static void Main(string[] args) {
    var t = int.Parse(Console.ReadLine());
    while (t-- > 0) {
        var arrAb = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        // number of places he needs to go
        var a = arrAb[0];
        // number of cab drivers
        var b = arrAb[0];
        var edges = new Edge[a];
        for (var i = 0; i < a; i++) {
            var edgeInput = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            edges[i] = new Edge() {Src = edgeInput[0], Dest = edgeInput[1]};
        }
        // Find the minimum number of edges to connect - Minimum spanning tree
        var ans = 0;
        // No need to sort because weights are not holding any value
        var uf = new UnionFind(b);
        for (var i = 0; i < a; i++) {
            var e = edges[i];
            if (!uf.IsConnected(e.Src, e.Dest)) {
                ans++;
                uf.Union(e.Src, e.Dest);
            }
        }
        Console.WriteLine(ans);
    }
}
    }
}

Show compiler warnings [ - ] Show input
Compilation time: 0,58 sec, absolute running time: 0,11 sec, cpu time: 0,14 sec, average memory usage: 18 Mb, average nr of threads: 3, absolute service time: 0,73 sec