#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'twoPluses' function below.
#
# The function is expected to return an INTEGER.
# The function accepts STRING_ARRAY grid as parameter.
#

def twoPluses(grid):
    # Write your code here
    n, m = len(grid), len(grid[0])
    up = [[0]*m for _ in range(n)]
    down = [[0]*m for _ in range(n)]
    left = [[0]*m for _ in range(n)]
    right = [[0]*m for _ in range(n)]
    for i in range(n):
        for j in range(m):
            if grid[i][j] == 'G':
                up[i][j] = 1 + (up[i-1][j] if i > 0 else 0)
                left[i][j] = 1 + (left[i][j-1] if j > 0 else 0)
    for i in reversed(range(n)):
        for j in reversed(range(m)):
            if grid[i][j] == 'G':
                down[i][j] = 1 + (down[i+1][j] if i < n-1 else 0)
                right[i][j] = 1 + (right[i][j+1] if j < m-1 else 0)

    pluses = []
    for i in range(n):
        for j in range(m):
            if grid[i][j] == 'G':
                arm_len = min(up[i][j], down[i][j], left[i][j], right[i][j]) - 1
                for length in range(arm_len + 1):
                    pluses.append((i, j, length, 4*length + 1))  # (row, col, arm, area)    
    def cells_of_plus(r, c, arm):
        cells = {(r, c)}
        for k in range(1, arm+1):
            cells.add((r+k, c))
            cells.add((r-k, c))
            cells.add((r, c+k))
            cells.add((r, c-k))
        return cells

    max_product = 0
    for i in range(len(pluses)):
        r1, c1, arm1, area1 = pluses[i]
        cells1 = cells_of_plus(r1, c1, arm1)
        for j in range(i+1, len(pluses)):
            r2, c2, arm2, area2 = pluses[j]
            cells2 = cells_of_plus(r2, c2, arm2)
            if cells1.isdisjoint(cells2):
                product = area1 * area2
                if product > max_product:
                    max_product = product
    return max_product


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

    first_multiple_input = input().rstrip().split()

    n = int(first_multiple_input[0])

    m = int(first_multiple_input[1])

    grid = []

    for _ in range(n):
        grid_item = input()
        grid.append(grid_item)

    result = twoPluses(grid)

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

    fptr.close()