20
.*..*...*....*.....*
 97
****.***.***.*..**.**.*.*.***.*............*..*......*.***.**.*.***.*.***.*..*.**.*.***.**.*****.
 5
*.***
 4
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 11
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 72
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 89
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 6
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 54
...***.*...****.*..****....*..**..**..***.*..**...**..
 100
****************************************************************************************************
 53
*.*.****.*.*......**....**.***.*.*.**.*.*.***...*..*.
 87
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 90
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 55
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 21
*.*...*.*...*.*...*.*
 41
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 31
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 64
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 10
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 99
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 69
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 99
.*.......................*.......................*.......................*.......................*.
 98
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 57
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 64
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 17
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 100
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 11
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 1
.
 100
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 56
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 99
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 10
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 51
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 17
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 97
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 42
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 5
*****
 42
..*...*.*..**..*.*.*..**...**.***.*.******
 71
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 5
.****
 99
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 42
.*.*...*..**.****...****..*.*.***....**...
 10
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 1
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 16
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 100
*.......................*.......................*.......................*.......................*...
 7
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 58
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 67
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 99
.*.......................*...............................................*.......................*.
 6
......
 11
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 15
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 75
..*.**..*.*****.......*....*.*.*..**.*.***.*.***....******.****.*.....****.
 45
.***..******....***..**..*.*.*.**..**..*.**..
 13
*..*..*..*..*
 5
**.**
 100
*****...............................................................................................
 99
..*.*..**.*.*.******.*.*.**.**.**.*..**.*.*****..*.*.****.*....**....*****.....***..**....***.*.*.*
 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
#!/usr/bin/env python
#-*- coding:utf-8 -*-

import sys, math, random, operator
from string import ascii_lowercase
from string import ascii_uppercase
from fractions import Fraction, gcd
from decimal import Decimal, getcontext
from itertools import product, permutations, combinations
from Queue import Queue, PriorityQueue
from collections import deque, defaultdict, Counter
getcontext().prec = 100

MOD = 10**9 + 7
INF = float("+inf")

if sys.subversion[0] != "CPython":  # PyPy?
    raw_input = lambda: sys.stdin.readline().rstrip()
pr = lambda *args: sys.stdout.write(" ".join(str(x) for x in args) + "\n")

read_str = raw_input
read_strs = lambda: raw_input().split()
read_int = lambda: int(raw_input())
read_ints = lambda: map(int, raw_input().split())
read_float = lambda: float(raw_input())
read_floats = lambda: map(float, raw_input().split())

"---------------------------------------------------------------"

n = read_int()
s = read_str()

for i in xrange(0, len(s)):
    for j in xrange(1, len(s)):
        if i + 4 * j >= len(s):
            break
        t = [s[i + k * j] for k in xrange(5)]
        if "".join(t) == "*****":
            print "yes"
            quit()

print "no"

