import java.io.*;

public class MaxSumOf3x3 {
    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String[] tokens = in.readLine().split(" ");
        int a = Integer.parseInt(tokens[0]);
        int b = Integer.parseInt(tokens[1]);
		int[][] array=new int[a][b];
		for(int i=0;i<b;i++){
			String[] numbers = in.readLine().split(" ");
			for(int j=0;j<a;j++){
				array[i][j]=Integer.parseInt(numbers[j]);
			}
		}
		int maxSum=0;
		int currentSum=0;
		for(int i=0;i<a-2;i++){
			for(int j=0;j<b-2;j++){
				currentSum=sum(array,i,j);
				if(maxSum<=currentSum){
					maxSum=currentSum;
				}
			}
		}
		System.out.println(maxSum);
    }
	public static int sum(int[][] arraySum,int row,int col){
		int sum=0;
		for(int i=row;i<row+3;i++){
			for(int j=col;j<col+3;j++){
				sum+=arraySum[i][j];
			}
		}
		return sum;
	}
}