local h,w=io.read("n","n","l")
local s={}
for i=1,h do
    local input=io.read()
    s[i]={}
    for j=1,w do
        s[i][j]=input:byte(j)
    end
end

local u,d,l,r={},{},{},{}
for j=1,w do
    for i=1,h do
        u[i]=u[i] or {}
        if s[i][j]==35 then
            u[i][j]=0
        else
            if i==1 then
                u[i][j]=1
            else
                u[i][j]=u[i-1][j]+1
            end
        end
    end
end
for j=1,w do
    for i=h,1,-1 do
        d[i]=d[i] or {}
        if s[i][j]==35 then
            d[i][j]=0
        else
            if i==h then
                d[i][j]=1
            else
                d[i][j]=d[i+1][j]+1
            end
        end
    end
end
for i=1,h do
    l[i]={}
    for j=1,w do
        if s[i][j]==35 then
            l[i][j]=0
        else
            if j==1 then
                l[i][j]=1
            else
                l[i][j]=l[i][j-1]+1
            end
        end
    end
end
for i=1,h do
    r[i]={}
    for j=w,1,-1 do
        if s[i][j]==35 then
            r[i][j]=0
        else
            if j==w then
                r[i][j]=1
            else
                r[i][j]=r[i][j+1]+1
            end
        end
    end
end

local max=0
for i=1,h do
    for j=1,w do
        max=math.max(max,u[i][j]+d[i][j]+l[i][j]+r[i][j]-3)
    end
end
print(max)