20
.*..*...*....*.....*
 97
****.***.***.*..**.**.*.*.***.*............*..*......*.***.**.*.***.*.***.*..*.**.*.***.**.*****.
 5
*.***
 4
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 11
.*.*.*.*...
 72
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 89
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 6
***.**
 54
...***.*...****.*..****....*..**..**..***.*..**...**..
 100
****************************************************************************************************
 53
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 87
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 90
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 55
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 21
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 41
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 31
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 64
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 10
*****....*
 99
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 69
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 99
.*.......................*.......................*.......................*.......................*.
 98
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 57
**...*....**.**.*.******.**..**.*.....**.***..***...**..*
 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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 42
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 71
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 99
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 42
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 10
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 1
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 5
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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
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 45
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 13
*..*..*..*..*
 5
**.**
 100
*****...............................................................................................
 99
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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
# 526A
# O(n^2) time
# θ(n) space

__author__ = 'artyom'


# SOLUTION

def main():
    n = read()
    s = read(0)
    for i in range(n - 4):
        j = 1
        while i + j * 4 < n:
            if s[i] == '*' and s[i + j] == '*' and s[i + 2 * j] == '*' and s[i + 3 * j] == '*' and s[i + 4 * j] == '*':
                return 'yes'
            j += 1
    return 'no'


# HELPERS

def read(mode=1, size=None):
    # 0: String
    # 1: Integer
    # 2: List of strings
    # 3: List of integers
    # 4: Matrix of integers
    if mode == 0: return input().strip()
    if mode == 1: return int(input().strip())
    if mode == 2: return input().strip().split()
    if mode == 3: return list(map(int, input().strip().split()))
    a = []
    for _ in range(size):
        a.append(read(3))
    return a


def write(s="\n"):
    if s is None: s = ''
    if isinstance(s, tuple) or isinstance(s, list): s = ' '.join(map(str, s))
    s = str(s)
    print(s, end="\n")


write(main())