#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

int nbCols, nbLignes;
int grille[500][500];
int plusMax[500][500];
const int dirs[4][2] = { {0, 1}, {1, 0}, {-1, 0}, {0, -1} };

const int INF = 2000000000;

bool estBord(int i, int j)
{
	return (i == 0 || i == nbLignes-1 || j == 0 || j == nbCols-1);
}

int main()
{
	scanf("%d%d", &nbCols, &nbLignes);

	for(int i = 0; i < nbLignes; i++)
	{
		for(int j = 0; j < nbCols; j++)
		{
			scanf("%d", &grille[i][j]);
			plusMax[i][j] = INF;
			if(estBord(i, j)) //bords
				plusMax[i][j] = grille[i][j];
		}
	}

	for(int k = 0; k < 30; k++) //hum, + ou - ? on va mettre un grand truc pour pas de pb et que ça passe ><
	for(int i = 0; i < nbLignes; i++)
	{
		for(int j = 0; j < nbCols; j++)
		{
			if(estBord(i, j))
				continue;

			int valBordMin = INF;

			for(int d = 0; d < 4; d++)
			{
				int x = j + dirs[d][0];
				int y = i + dirs[d][1];

				if(x >= 0 && x < nbCols && y >= 0 && y < nbLignes)
					valBordMin = min(valBordMin, plusMax[y][x]);
			}

			plusMax[i][j] = std::max(grille[i][j], valBordMin);
		}
	}

	int total = 0;

	for(int i = 0; i < nbLignes; i++)
		for(int j = 0; j < nbCols; j++)
			total+=plusMax[i][j]-grille[i][j];

	printf("%d\n", total);

	return 0;
}