Messagen = input()

n = input() s = input() k = [] temp = [] for i in range(len(s)):     if s[i] == '.':         temp.append(i+1)             if s[i] == '#' and len(temp) != 0 or i == len(s)-1 and s[i] == '.':         k.append(temp)         temp = [] k.sort(key=len, reverse= True) print(k[0][len(k[0])//2]) #C #Python_Online