N = int(input())
S = input()
onlyb = 0
onlyw = 0
twotn = 0
flag = 0
ch =0
for i in range(N):
    if S[i] == ".":
        onlyb += 1
        ch = 0
        if flag != 0:
            twotn +=1
    else:
        onlyw += 1
        ch +=1
        flag = 1

print(min(onlyb,onlyw-ch,twotn))