import itertools

n=int(input())
s=list(input())
v=list(reversed(s))
ans=float('inf')
s1=[]

s=itertools.accumulate(s)
v=itertools.accumulate(v)
s=['']+list(s)
v=['']+list(v)

for i in range(n):
    cnt=s[i].count('#')+v[-(i+1)].count('.')
    ans=min(cnt,ans)
print(ans)


    

    
        
        
        
    
                
    
        

     

    

     

    
