#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'connectedCell' function below.
#
# The function is expected to return an INTEGER.
# The function accepts 2D_INTEGER_ARRAY matrix as parameter.
#

def connectedCell(matrix):
    # Write your code here
    ones = []
    for i in range(len(matrix)):
        for j in range(len(matrix[0])):
            if matrix[i][j] == 1:
                ones.append((i, j))
    l = []
    while ones != []:
        one = ones.pop(0)
        ll = [one]
        m = 1
        n = 0
        while n != m:
            m = len(ll)
            for one in ll:
                i, j = one[0], one[1]
                neighbors = [(i-1, j-1), (i-1, j), (i-1, j+1), (i, j-1), (i, j+1), (i+1, j-1), (i+1, j), (i+1, j+1)]
                for neighbor in neighbors:
                    if neighbor in ones:
                        ones.remove(neighbor)
                        ll.append(neighbor)
            n = len(ll)
        l.append(len(ll))   
    return max(l)

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input().strip())

    m = int(input().strip())

    matrix = []

    for _ in range(n):
        matrix.append(list(map(int, input().rstrip().split())))

    result = connectedCell(matrix)

    fptr.write(str(result) + '\n')

    fptr.close()