using System;

public class Program

{

    public static int NhapN(string note) {

        Console.WriteLine(note);

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

        return n;

    }

    public static double[,] NhapMaTran(string note) {

        double[,] arr;

        int n = NhapN("Nhap cot n: ");

        int m = NhapN("Nhap dong n: ");

        arr = new int[n, m];

        for (int i = 0; i < arr.GetLength(0); i++) {

            for (int j = 0; j < arr.GetLength(1); j++) {

                arr[i, j] = double.Parse(Console.ReadLine());

            }

        }

        return arr;

    }

    public static void XuatMaTran(int[,] arr) {

        for (int i = 0; i < arr.GetLength(0); i++) {

            for (int j = 0; j < arr.GetLength(1); j++) {

                Console.Write(arr[i, j] + " ");

            }

            Console.WriteLine();

        }

    }

    public static double TongSoAm(double[,] arr) {

        double sum = 0;

        for (int i = 0; i < arr.GetLength(0); i++) {

            for (int j = 0; j < arr.GetLength(1); j++) {

                if (arr[i, j] < 0) {

                    sum+=arr[i, j];

                }

            }

        }

        return sum;

    }

    public static void Main()

    {

        double[,] arr;

        arr = NhapMaTran("Nhap ma tran: ");

        double result = TongSoAm(arr);

        Console.Write(result);

    }

}