N = int(input())
S = input()

if len(set(S)) == 1:
    print(0)
    quit()

a = S.count(".")
b = S.count("#")
ans2 = min(a,b)

ans = 0

if S[0] == "#":
    i = 1
    while True:
        if S[i] == ".":
            ans = i
            S = S[i:]
            break
        else:
            i += 1
else:
    flag = False
    for i in S:
        if i == "#":
            flag = True
        elif flag :
            break
    else:
        print(0)
        quit()

# if len(set(S)) == 1:
#     print(ans2)
#     quit()

if S[-1] == ".":
    i = 2
    while True:
        if S[-i] == "#":
            ans += (i-1)
            S = S[:-i+1]
            break
        else:
            i += 1


for i in range(len(S)):
    if S[i] == "#":
        S = S[i:]
        break
for i in range(1, len(S)+1):
    if S[-i] == ".":
        S = S[:-(i-1)]
        break

print(min(min(S.count("."), S.count("#")) + ans, ans2))