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 99
***************************************************************************************************
 5
****.

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
from __future__ import print_function

def try_hop(field, i):
	for slice_len in xrange(1, len(field)+1):
		res = field[i::slice_len]
		#print(i, slice_len, res)
		if len(res) == 5 and set(res) == {'*'}:
			return slice_len
	return 0

def main():
	n = int(raw_input())
	field = raw_input()
	win = False
	for i in xrange(n):
		if field[i] != '.':
			slice_len = try_hop(field, i)
			if slice_len:
				j = i+4*slice_len
				#print(j)
				if j+slice_len >= n or field[j+slice_len] == '*':
					win = True
					break
	if win:
		print('yes')
	else:
		print('no')

if __name__ == '__main__':
	main()

