# -*- coding: utf-8 -*-

trial_num = int(input())
stones = list(input())

min_turn_stones = 2 * 10 ** 5

for i in range(trial_num):
    if(stones[i] == "."):
        tmp_min = stones[:i].count("#") + stones[i+1:].count(".")
        if (tmp_min < min_turn_stones):
            min_turn_stones = tmp_min

print(min_turn_stones)