H, W = gets.split.map(&:to_i)
Ss = Array.new(H) { gets.chomp }

left = Hash.new{|hash, key| hash[key] = []}
right = Hash.new{|hash, key| hash[key] = []}
up = Hash.new{|hash, key| hash[key] = []}
down = Hash.new{|hash, key| hash[key] = []}

0.upto(H-1){|i| 
    0.upto(W-1){|j|
        if (Ss[i][j] === "#")
            left[i][j] = 0
            next
        end
        if (j === 0)
            left[i][j] = 1
            next
        end
        left[i][j] = left[i][j-1] + 1
    }

    (W-1).downto(0){|j|
        if (Ss[i][j] === "#")
            right[i][j] = 0
            next
        end
        if (j === W-1)
            right[i][j] = 1
            next
        end
        right[i][j] = right[i][j+1] + 1
    }

    0.upto(W-1){|j|
        if (Ss[i][j] === "#")
            up[i][j] = 0
            next
        end
        if (i === 0)
            up[i][j] = 1
            next
        end
        up[i][j] = up[i-1][j] + 1
    }
}

(H-1).downto(0){|i| 
    0.upto(W-1){|j|
        if (Ss[i][j] === "#")
            down[i][j] = 0
            next
        end
        if (i === H-1)
            down[i][j] = 1
            next
        end
        down[i][j] = down[i+1][j] + 1
    }
}

ans = 0
tmp = 0
0.upto(H-1){|i| 
    0.upto(W-1){|j|
        tmp = 0
        tmp += left[i][j] if j != 0
        tmp += right[i][j] if j != W-1
        tmp += up[i][j] if i != 0
        tmp += down[i][j] if i != H-1
        ans = [ans,tmp-3].max
    }
}

puts ans
