local function str2tbl(s)
    local t = {string.byte(s, 1, #s)}
    for i=1, #t do
        t[i] = string.char(t[i])
    end
    return t
end

local function str2numtbl(s, offset)
    local t = {string.byte(s, 1, #s)}
    if offset then
        for i=1, #t do
            t[i] = t[i] - offset
        end
    end
    return t
end

--local function each_char2(s)
--    return ipairs(str2tbl(s))
--end

local function each_char(s)
    local f = function(_, i)
        i = i + 1
        if i <= #s then
            return i, string.sub(s, i, i)
        end
    end
    return f, nil, 0
end

function string.at(s, i)
    return string.sub(s, i, i)
end

--
local N,_,S = io.read("n", "l", "l")
local B = '#'
local W = '.'
S = str2tbl(S)
local ans = 0
local flag = false
for i=1,N do
    local c = S[i]
    if not flag then
        if c == B then
            flag = true
        end
    else
        if c == W then
            ans = ans + 1
        end
    end
end
print(ans)