namespace JediGalaxy
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Numerics;

    class Program
    {
        static void Main(string[] args)
        {
            var dimensions = ParseInput(Console.ReadLine());

            var rows = dimensions[0];
            var cols = dimensions[1];

            var matrix = new int[rows][];
            FillMatrix(matrix,rows,cols);

            var input = Console.ReadLine();
            BigInteger collectedStarsSum = 0;
            var starsHittedByEvil = new Dictionary<int, HashSet<int>>();

            while (input != "Let the Force be with you")
            {
                var ivoCoordinates = ParseInput(input);
                var evilCoordinates = ParseInput(Console.ReadLine());

                CollectStars(matrix, ivoCoordinates, evilCoordinates, ref collectedStarsSum, starsHittedByEvil);

                input = Console.ReadLine();
            }

            Console.WriteLine(collectedStarsSum);
        }

        private static void CollectStars(int[][] matrix, int[] ivoCoordinates, int[] evilCoordinates, ref BigInteger collectedStarsSum, Dictionary<int, HashSet<int>> starsHittedByEvil)
        {
            var ivoRow = ivoCoordinates[0];
            var ivoCol = ivoCoordinates[1];

            var evilRow = evilCoordinates[0];
            var evilCol = evilCoordinates[1];

            HitStars(matrix, evilRow, evilCol, starsHittedByEvil);

            for (int r = ivoRow; r >= 0; r--)
            {
                if (ivoCol < 0 || r >= matrix.Length)
                {
                    ivoCol++;
                    continue;
                }

                if (ivoCol >= matrix[0].Length)
                {
                    break;
                }

                if (!starsHittedByEvil.ContainsKey(r) || !starsHittedByEvil[r].Contains(ivoCol))
                {
                    collectedStarsSum += matrix[r][ivoCol];
                }

                ivoCol++;
            }
        }

        private static void HitStars(int[][] matrix, int evilRow, int evilCol, Dictionary<int, HashSet<int>> starsHittedByEvil)
        {
            for (int r = evilRow; r >= 0; r--)
            {
                if (evilCol >= matrix[0].Length || (r >= matrix.Length))
                {
                    evilCol--;
                    continue;
                }

                if (evilCol < 0)
                {
                    break;
                }

                if (!starsHittedByEvil.ContainsKey(r))
                {
                    starsHittedByEvil.Add(r, new HashSet<int>());
                }
                starsHittedByEvil[r].Add(evilCol);

                evilCol--;
            }
        }

        private static void FillMatrix(int[][] matrix, int rows, int cols)
        {
            int num = 0;

            for (int r = 0; r < rows; r++)
            {
                matrix[r] = new int[cols];
                for (int c = 0; c < cols; c++)
                {
                    matrix[r][c] = num++;
                }
            }
        }

        private static int[] ParseInput(string input)
        {
            return input
                .Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
                .Select(int.Parse)
                .ToArray();
        }
    }
}