import sys
input = sys.stdin.readline
import numpy as np

H, W = map(int, input().split())
S = np.array([list(input()) for _ in range(H)]) == '.'
ups = np.zeros((H,W), dtype=int)
downs = np.zeros((H,W), dtype=int)
lefts = np.zeros((H,W), dtype=int)
rights = np.zeros((H,W), dtype=int)

for h in range(H):
    ups[h] = (ups[h-1] + 1) * S[h-1]
    downs[H-h-1] = (downs[H-h-1] + 1) * S[H-h-1]
for w in range(W):
    lefts[:, w] = (lefts[:, w-1] + 1) * S[w-1]
    rights[:, W-w-1] = (rights[:, W-w-1] + 1) * S[W-w-1]
print(np.amax((ups+downs+lefts+rights)*S)+1)
