dfs grid

from collections import deque
def getBiggestRegion(grid):
  def size(i, j):
    if 0 <= i < len(grid) and 0 <= j < len(grid[i]) and grid[i][j] == 1:
      grid[i][j] = 0
      counter = sum([size(i2,j2) for i2 in range(i-1, i+2) for j2 in range(j-1, j+2)])
      return 1 + counter
    return 0
  return(max( size(a,b) for a in range(len(grid)) for b in range( len(grid[a])) ))
      
  
n = int(input().strip())
m = int(input().strip())
grid = []
for grid_i in range(n):
    grid_t = list(map(int, input().strip().split(' ')))
    grid.append(grid_t)
print(getBiggestRegion(grid))