Gauss

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


namespace Gauss
{
    class Program
    {
        static List<List<double>> GetMatrix()
        {
            StreamReader fin = new StreamReader("input.txt");
            int n = int.Parse(fin.ReadLine());
            int m = int.Parse(fin.ReadLine());

            List<List<double>> matrix = new List<List<double>>();

            for (int i = 0; i < n; i++)
            {
                List<double> tmp = new List<double>();
                string[] line = fin.ReadLine().Split(' ');
                for (int j = 0; j < m; j++)
                    tmp.Add(double.Parse(line[j]));
                matrix.Add(tmp);
            }

            fin.Close();

            return matrix;
        }

        static void RightProcess(List<List<double>> matrix)
        {
            double diagonalElem = 0;
            int count = matrix.Count + 1;
            double firstElem = 0;

            for (int i = 0; i < matrix.Count; i++)
            {
                diagonalElem = matrix[i][i];
                if (diagonalElem != 0)
                {
                    for (int j = i; j < count; j++)
                        matrix[i][j] /= diagonalElem;

                    for(int j = i + 1; j < matrix.Count; j++)
                    {
                        firstElem = matrix[j][i];
                        for (int k = i; k < count; k++)
                            matrix[j][k] -= matrix[i][k] * firstElem;
                    }
                }
                else throw new Exception("Matrix have null diagonal element!");
            }
        }

        static void BackProcess(List<List<double>> matrix)
        {
            int current = matrix.Count - 1;

            for (int i = matrix.Count - 2; i >= 0; i--)
            {
                for (int j = matrix.Count; j >= 0; j--)
                {
                    for(int k = 0; k <= i; k++)

                        matrix[k][j] -= matrix[i + 1][j] * matrix[k][current];
                }
                current--;
            }

            for (int i = matrix.Count - 1; i >= 0; i--)
                Console.Write("{0} ", matrix[i][matrix.Count]);
            Console.WriteLine();

        }

        static void Main(string[] args)
        {
            List<List<double>> matrix = GetMatrix();
            RightProcess(matrix);
            BackProcess(matrix);
        }
    }
}