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****.

no yes no no no yes yes no yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes yes no no no yes yes yes yes no no yes yes yes yes yes no yes yes no no no yes yes no yes yes no no no yes yes yes yes no yes yes yes no
__author__ = 'Shayan'
N=int(input())
dict=[]
diff=[]
dict1={}
list1 = raw_input()
pairs=0
#print(list1)
for x in range(0,N):
   if(list1[x]=='*'):
        dict.append(x+1)
#print dict
for i in range(0,len(dict)):
    diff=[]
    for j in range(i+1,len(dict)):
        if(dict[i]!=dict[j]):
            #print("i-->"+str(dict[i]))
            #print("j-->"+str(dict[j]))
            diff.append(abs(dict[j]-dict[i]))
    dict1[i]=diff
#print(dict1)
dict2={}
j=0
for k in range(0,len(dict1)):
    dict2[k]=[]
    for i in range(0,len(dict1)):
        tempdiff=dict1[i]
        if(j<len(tempdiff)):
            temp=tempdiff[j]
            dict2[k].append(temp)
    j+=1
#print(dict2)
dict3={}
for i in range(0,len(dict2)):
    temp=dict2[i];
    for j in (temp):
        dict3[j]=temp.count(j)
ohyes=0
for i in dict3.keys():
    if(dict3[i]==4 and i!=1):
        ohyes=1
if(ohyes==1):
    print "yes"
else:
    print "no"
"""if(pairs>=2):
    print('yes')
else:
    print("no")
print(dict3)"""