SHPATH - NZEC - Confusion

[leppyr64]

Hi, I've been trying to solve this problem. It runs fine in visual studio, but I keep getting an NZEC on the judge.

Is there any way to find out from the judge where the error occurred?

Any help would be appreciated.

using System;
using System.Collections;
class SHPATH
{
	#region "Struct Node"
	// Item to be used in priority queue
	public struct Node
	{
		public int ID, Cost;
    	public Node(int NewID, int NewCost)
	{
		ID = NewID;
		Cost = NewCost;
	}

	public static bool operator <(Node a, Node b)
	{
		if(b.Cost > a.Cost) return true;
		else return false;
	}

	public static bool operator >(Node a, Node b)
	{
		if(a.Cost > b.Cost) return true;
		else return false;
	}
}
#endregion

#region "Main Program"
public static void Main()
{
	string[] cities = new string[10001];
	int[,] edges = new int[10001, 10001]; //[from, to]
	int[] bestCost = new int[10001];
	ArrayList q = new ArrayList();	

	int nTests = int.Parse(Console.ReadLine());

	while (nTests-- > 0)
	{
		int nCities = int.Parse(Console.ReadLine());

		for(int i = 1; i <= nCities; i++)
		{
			for (int j = 1; j <= nCities; j++)
				edges[i, j] = 200000; // maximum value for a path, prevents travel

			cities[i] = Console.ReadLine();
			int nRoads = int.Parse(Console.ReadLine());

			for(int j = 1; j <= nRoads; j++)
			{
				string[] s = Console.ReadLine().Split(' ');
				int dest = int.Parse(s[0]);
				edges[i,dest] = int.Parse(s[1]);
			}
		}

		int nChecks = int.Parse(Console.ReadLine());
		for(int i = 1; i <= nChecks; i++)
		{
			string [] s = Console.ReadLine().Split(' ');

			string c1 = s[0];
			string c2 = s[1];

			int idxC1 = 0;
			int idxC2 = 0;

			for (int j = 1; j <= nCities; j++)
			{
				bestCost[j] = 200000; // maximum cost for a path
				if (cities[j] == c2)
					idxC2 = j;
				else if (cities[j] == c1)
					idxC1 = j;
			}
			
			q.Add(new Node(idxC1, 0));
			while (q.Count > 0)
			{
				Node p = (Node)q[0];
				q.RemoveAt(0);
				if (p.Cost < bestCost[p.ID])
				{
					bestCost[p.ID] = p.Cost;
					for (int j = 1; j <= nCities; j++)
					{
						if (p.Cost + edges[p.ID, j] < bestCost[j])
						{
							Node l = new Node(j, p.Cost + edges[p.ID, j]);
							bool added = false;
							for (int k = 0; k < q.Count; k++)
							{
								if (l < (Node)q[k])
								{
									added = true;
									q.Insert(k, l);
									break;
								}
							}
							if (!added) q.Add(l);
						}
					}
				}
			}
			Console.WriteLine(bestCost[idxC2]);
		}
		if(nTests > 0) Console.ReadLine();
	}
}
#endregion
}