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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
def play(n, s):

    max_d = (n-1)/4

    if n <= 4:
       print "no"
       return
   
    for i in range(1,max_d+1):
       for p in range(n-i*4):
          if s[p]=='*' and s[p+i] =='*' and s[p+2*i]=='*' and s[p+3*i]=='*' and s[p+4*i]=='*':
              print "yes"
              return

    print "no"

if __name__=="__main__":
    n = int(raw_input())
    s = raw_input()

    play(n,s)



