N=int(input())
S=list(input())
dot=0
sha=0
s_r=list(reversed(S))
#print(s_r)
for i in range(N):
    if S[i] == ".":
        dot=i
        #break
for i in range(N):
    if s_r[i] == "#":
        sha=i
        #break

count=0
#print(dot)#左から
#print(sha)#右から
count_a=0
count_b=0
#d=10**
for i in range(N):
    if i<dot and S[i]!=".":
        count_a+=1
for i in range(N):
    if i<sha and s_r[i]!="#":
        count_b+=1
#print(count)
if dot<=sha:
    c=count_a+count_b
else:
    c=min(count_a,count_b)

a=0
b=0

for i in range(N):
    if S[i]!=".":
        a+=1
    if S[i]!="#":
        b+=1

#print(count)
ans=min(a,b,c)
print(ans)

