n = int(input())
s = input()
a = []
#  .##..#.##.
w = s.count(".")
b = s.count("#")
m = min(w,b)

bb=0

for i in range(n):
    if s[i]=='.':
        w-=1
    if s[i]=='#':
        bb += 1
        a.append(bb+w)
if len(a)>0:
    I = min(a)
    print(min(m,I))
else:
    print(m)
