#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    int H, W;
    std::cin >> H >> W;

    // Create a 2D vector to represent the grid
    std::vector<std::vector<int>> A(H + 2, std::vector<int>(W + 2, 0));

    // Input the values of the inner grid
    for (int i = 1; i <= H; ++i) {
        for (int j = 1; j <= W; ++j) {
            std::cin >> A[i][j];
        }
    }

    // Initialize the maximum sum to 0
    int maxSum = 0;

    // Iterate over all possible beam directions
    for (int dx1 = -1; dx1 <= 1; ++dx1) {
        for (int dy1 = -1; dy1 <= 1; ++dy1) {
            for (int dx2 = -1; dx2 <= 1; ++dx2) {
                for (int dy2 = -1; dy2 <= 1; ++dy2) {
                    // Skip cases where both directions are (0, 0) or the same
                    if ((dx1 == 0 && dy1 == 0) || (dx2 == 0 && dy2 == 0) || (dx1 == dx2 && dy1 == dy2)) {
                        continue;
                    }

                    // Initialize a temporary grid to store destroyed values
                    std::vector<std::vector<int>> tempGrid(A);

                    // Perform the first beam operation
                    for (int x = 1; x <= H; ++x) {
                        for (int y = 1; y <= W; ++y) {
                            if (x + dx1 >= 0 && x + dx1 <= H + 1 && y + dy1 >= 0 && y + dy1 <= W + 1) {
                                tempGrid[x + dx1][y + dy1] = std::max(tempGrid[x + dx1][y + dy1], A[x][y]);
                            }
                        }
                    }

                    // Perform the second beam operation
                    for (int x = 1; x <= H; ++x) {
                        for (int y = 1; y <= W; ++y) {
                            if (x + dx2 >= 0 && x + dx2 <= H + 1 && y + dy2 >= 0 && y + dy2 <= W + 1) {
                                tempGrid[x + dx2][y + dy2] = std::max(tempGrid[x + dx2][y + dy2], A[x][y]);
                            }
                        }
                    }

                    // Calculate the sum of destroyed values
                    int sum = 0;
                    for (int x = 1; x <= H; ++x) {
                        for (int y = 1; y <= W; ++y) {
                            if (tempGrid[x][y] > A[x][y]) {
                                sum += tempGrid[x][y] - A[x][y];
                            }
                        }
                    }

                    // Update the maximum sum
                    maxSum = std::max(maxSum, sum);
                }
            }
        }
    }

    std::cout << maxSum << std::endl;

    return 0;
}