#! /usr/bin/env python3

# from fractions import gcd
from math import gcd
from collections import Counter, deque, defaultdict
from heapq import heappush, heappop, heappushpop, heapify, heapreplace, merge
from bisect import bisect_left, bisect_right, bisect, insort_left, insort_right, insort
from itertools import accumulate, product, permutations, combinations, combinations_with_replacement
from collections import Counter, deque, defaultdict

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

mi = 10000000

c = Counter(S)
A = N - c["#"]
B = N - c["."]

for i in range(1, N):
    l = S[:i]
    r = S[i:]
    a = l.count("#") + r.count(".")
    if mi > a:
        mi = a

print(min(mi, A, B))
