from numpy import*
from itertools import*
n=int(input())
s=input()
t=s.count("#")
r=s.count(".")

l=[t,r]
x=[len(list(v))for k,v in groupby(s)if k=="#"]
y=[len(list(v))for k,v in groupby(s)if k=="."]
if len(x)>len(y):
    y=[0]+y
elif len(x)<len(y):
    x=[0]+x
else:
    if s[0]=="#":
        y=[0]+y
        x=x+[0]
    else:
        y=y+[0]
        x=[0]+x
x=array(list(accumulate(x)))
y=array(list(accumulate(y[::-1]))[::-1])
print(min(x+y))