package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func COM(n, k int64) int64 {
	r := int64(1)
	for i := int64(0); i < k; i++ {
		r = ModMul(r, n-i)
		r = ModDiv(r, i+1)
	}

	return r
}

const (
	MOD = 1000000000 + 7
)

func ModAdd(a, b int64) int64 {
	return (a + b) % MOD
}

func ModMul(a, b int64) int64 {
	return a * b % MOD
}

func ModSub(a, b int64) int64 {
	r := (a%MOD - b%MOD) % MOD
	if r < 0 {
		r += MOD
	}
	return r
}

func ModDiv(a, b int64) int64 {
	return a % MOD * ModInv(b) % MOD
}

func ModPow(a, n int64) int64 {
	var r int64 = 1
	for n > 0 {
		if n&1 == 1 {
			r = r * a % MOD
		}
		a = a * a % MOD
		n >>= 1
	}
	return r
}

func ModInv(a int64) int64 {
	var b, u, v int64 = MOD, 1, 0
	for b > 0 {
		t := a / b
		a -= t * b
		a, b = b, a
		u -= t * v
		u, v = v, u
	}
	u %= MOD
	if u < 0 {
		u += MOD
	}
	return u
}

type Q struct {
	value int
	index int
	A, B  int
}

type QS []*Q

func (p QS) Len() int           { return len(p) }
func (p QS) Less(i, j int) bool { return p[i].value > p[j].value }
func (pq QS) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
	pq[i].index = i
	pq[j].index = j
}

func (pq *QS) Push(x interface{}) {
	n := len(*pq)
	item := x.(*Q)
	item.index = n
	*pq = append(*pq, item)
}

func (pq *QS) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	old[n-1] = nil  // avoid memory leak
	item.index = -1 // for safety
	*pq = old[0 : n-1]
	return item
}

func FactoredPrimeNumber(num int) map[int]int {
	m := map[int]int{}
	return factor(m, num, 2)
}

func factor(result map[int]int, num, pnum int) map[int]int {
	if pnum*pnum > num {
		if num != 1 {
			result[num] += 1
		}
		return result
	}

	if num%pnum == 0 {
		num /= pnum
		result[pnum]++
	} else {
		pnum++
	}
	return factor(result, num, pnum)
}

func GCD(a, b int64) int64 {
	if b == 0 {
		return a
	}
	return GCD(b, a%b)
}

func LCM(a, b int64) int64 {
	return a * b / GCD(a, b)
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Scan()
	t := strings.Split(sc.Text(), " ")
	H, _ := strconv.Atoi(t[0])
	W, _ := strconv.Atoi(t[1])

	Up := [2100][2100]int{}
	Down := [2100][2100]int{}
	Left := [2100][2100]int{}
	Right := [2100][2100]int{}

	RS := make([][]rune, H)
	for i := 0; i < H; i++ {
		sc.Scan()
		RS[i] = []rune(sc.Text())
	}

	for i := 0; i < H; i++ {
		cnt := 0
		for j := 0; j < W; j++ {
			s := string(RS[i][j])
			if s == "#" {
				cnt = 0
			} else {
				cnt++
				Left[i][j] = cnt
			}
		}
		cnt = 0
		for j := W - 1; j >= 0; j-- {
			s := string(RS[i][j])
			if s == "#" {
				cnt = 0
			} else {
				cnt++
				Right[i][j] = cnt
			}
		}
	}
	for i := 0; i < W; i++ {
		cnt := 0
		for j := 0; j < H; j++ {
			s := string(RS[j][i])
			if s == "#" {
				cnt = 0
			} else {
				cnt++
				Down[i][j] = cnt
			}
		}
		cnt = 0
		for j := H - 1; j >= 0; j-- {
			s := string(RS[j][i])
			if s == "#" {
				cnt = 0
			} else {
				cnt++
				Up[i][j] = cnt
			}
		}
	}

	max := 0

	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			score := Left[i][j] + Right[i][j] + Up[j][i] + Down[j][i] - 3
			if score > max {
				max = score
			}
		}
	}

	fmt.Println(max)
}

func Reverse(runes []rune) []rune {
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return runes
}


Measured memory_bytes: 163968