N=int(input())
S=str(input())

s1=[]
s2=[]
a_min=float('inf')
a=0

for i in range(N+1):
    s1=S[:i]
    s2=S[i:]
    a=min(s1.count('.'),s1.count('#'))+s2.count('.')
    if a<a_min:
        a_min=a
        
print(a_min)