20
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 97
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 5
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 53
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 57
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 17
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 100
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 11
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 1
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 100
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 56
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 99
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 51
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 71
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***************************************************************************************************
 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/python
__author__ = 'Acesine'


def solve(line):
    pos = []
    for i in range(len(line)):
        if line[i] == '*':
            pos.append(i)
    if len(pos) < 5:
        return False
    l = len(pos)
    for i in range(l):
        start = pos[i]
        for j in range(l)[i+1:]:
            step = pos[j] - pos[i]
            flag = True
            for c in range(5):
                if start + step * c not in pos:
                    flag = False
                    break
            if flag:
                return True
    return False



raw_input()
seg = raw_input()
if solve(seg):
    print "yes"
else:
    print "no"

