n=int(input())
s=list(input())
nod=[]
for i in range(n):
    if s[i]=="#":
        nod.append(i+1)
dp=[-1]*(n+3)
for ind in range(len(nod)-1,-1,-1):
    i=nod[ind]
    if ind==len(nod)-1:
        dp[i]=n-i+1
        continue
    j=nod[ind+1]
    t=dp[j]-1
    ni=i+t
    if ni<n-1:
        dp[i]=t+(n-ni+1)
    else:
        dp[i]=dp[j]+2
print(dp[nod[0]])