Journey To Moon

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {
    static void PrintRoots(int[] keys, int size){
        Console.WriteLine();
        Console.Write("Keys: ");
        for(int i = 0;i<size;i++){
            Console.Write(keys[i]+",");
        }
        Console.WriteLine();
    }
    static void PrintCountries(Dictionary<int,HashSet<int>> allCountries){
        Console.WriteLine("Countries: ");
        foreach(int key in allCountries.Keys){
            foreach(var key2 in allCountries[key]){
                Console.Write(key2+",");
            }
            Console.WriteLine();
        }
        Console.WriteLine();
    }
    static Int64 journeyToMoon(int n, int[][] astronaut) {
        // Complete this function
        Dictionary<int,HashSet<int>> allCountries = new Dictionary<int,HashSet<int>>();
        int[] roots = new int[n];
        Int64 totalCombinations = 0;

        for(int i = 0;i<n;i++){
            HashSet<int> tempSet = new HashSet<int>();
            tempSet.Add(i);
            allCountries.Add(i,tempSet);
            roots[i]=i;
        }
        for(int i=0;i<astronaut.Length;i++){
            int lesser,greater;

            if(astronaut[i][0]<astronaut[i][1]){
                lesser = astronaut[i][0];
                greater = astronaut[i][1];
            }else{
                lesser = astronaut[i][1];
                greater = astronaut[i][0];
            }

            if(!allCountries.ContainsKey(lesser)) lesser = roots[lesser];
            if(!allCountries.ContainsKey(greater)) greater = roots[greater];

            allCountries[roots[lesser]].UnionWith(allCountries[roots[greater]]);
            foreach(int key in allCountries[greater]){
                roots[key] = roots[lesser];
            }
            if(roots[greater]!=greater) allCountries.Remove(greater);
            //PrintRoots(roots,n);
            //PrintCountries(allCountries);
        }

        Int64 prevTotal = 0;
        foreach(var key in allCountries.Keys){
            if(prevTotal == 0){
                prevTotal = allCountries[key].Count;
            }else{
                totalCombinations+=(allCountries[key].Count*prevTotal);
                prevTotal += allCountries[key].Count;
            }
        }

        return totalCombinations;
    }

    static void Main(String[] args) {
        string[] tokens_n = Console.ReadLine().Split(' ');
        int n = Convert.ToInt32(tokens_n[0]);
        int p = Convert.ToInt32(tokens_n[1]);
        int[][] astronaut = new int[p][];
        for(int astronaut_i = 0; astronaut_i < p; astronaut_i++){
           string[] astronaut_temp = Console.ReadLine().Split(' ');
           astronaut[astronaut_i] = Array.ConvertAll(astronaut_temp,Int32.Parse);
        }
        Int64 result = journeyToMoon(n, astronaut);
        Console.WriteLine(result);
    }
}