20
.*..*...*....*.....*
 97
****.***.***.*..**.**.*.*.***.*............*..*......*.***.**.*.***.*.***.*..*.**.*.***.**.*****.
 5
*.***
 4
****
 11
.*.*.*.*...
 72
.***.**.*.*...*****.*.*.*.*.**....**.*.**..*.*...**..***.**.**..*.**..**
 89
..**..**..*.********....*.*****.**.****...*......*******..*.**.*****..*..****....*...**..
 6
***.**
 54
...***.*...****.*..****....*..**..**..***.*..**...**..
 100
****************************************************************************************************
 53
*.*.****.*.*......**....**.***.*.*.**.*.*.***...*..*.
 87
*..*..***.**.*...****...*....***....***......*..*.*.*****.**..*.***...*.****..**.*..***
 90
**....****.***..***.*.*****...*.*.***..***.******.**...***..*...*****..*.**.**...*..**...*
 55
...*..*.*.**..*.*....*.****..****....*..***.*****..*..*
 21
*.*...*.*...*.*...*.*
 41
*******....*..*.**..***.*...****.***.*...
 31
.******.**.**....*.*********...
 64
*.***...**...*..*...*....*..***.*.*.*.***.*.**...**.*.*.*..*....
 10
*****....*
 99
**...*.*.*..*....**.***..*...***..***.**.*.....*.*....*...*.**.**.****..**..*.*..*.***....**...**.*
 69
.***...*.***.**...*....*.***.*..*....**.*...**....*.*..**....**..*.**
 99
.*.......................*.......................*.......................*.......................*.
 98
.**..**.*****..***...*.**..*..*....*******..**....*.****.**.*.....*.**..***.**..***.*******..****.
 57
**...*....**.**.*.******.**..**.*.....**.***..***...**..*
 64
***.*...*...*.***.....*.....**.*****.*.*...*..*.*..***..*...***.
 17
*...*...*...*...*
 100
*...............................................................................................****
 11
*...**..*.*
 1
.
 100
*.....................*.....................*.....................*.....................*...........
 56
**.*..*...***.*.**.**..**.*.*.*.**...*.**.**....*...**..
 99
***....*.....****.*.**.*.*.**.*.*.*..*...*..*...***..*.*...*.*...***.*.*...**.**.*******....**....*
 10
.*.*.*.*.*
 51
....****....*........*.*..**........*....****....*.
 17
.*..*..*.....*..*
 97
...*..*...*******.*.**..**..******.*.*..*****.*...***.*.**.**.**..**.******.****.*.***.**..*...**
 42
***.*..*.*.***...**..*..**....**..*..*...*
 5
*****
 42
..*...*.*..**..*.*.*..**...**.***.*.******
 71
**.**..*****.*.*.*.********.....*****.****.*..***...*.*.*.**.****.**.**
 5
.****
 99
.*..**..*..*..**...***.****.*...*....*****.....**..****.*..*....****..**..*****..*....**.*.**..**..
 42
.*.*...*..**.****...****..*.*.***....**...
 10
.*.*.*.*..
 1
*
 5
***.*
 16
*.**.**.**.*..*.
 100
*.......................*.......................*.......................*.......................*...
 7
***.***
 58
**.*.*.**..******.**.*..*.**.*.*******.**.*.**.*..*****.*.
 67
..**.*...*.....****.***.**.*....***..***.*..***.....*******.....*.*
 99
.*.......................*...............................................*.......................*.
 6
......
 11
.**.*..*.**
 15
..........*****
 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
n = int(input())
layout = input()
good = False
num = 2
def check(n1, n2):
    global good 
    global num
    k = n2 - n1
    extra = n2 - n1
    while n2 + k < n:
        if layout[n2+k] != "*":
            good = False
            break
        else:
            k += extra
            good = True
            num += 1
for n1 in range(0, n):
    for n2 in range(0, n):
        num = 2
        if layout[n1] == "*" and layout[n2] == "*" and n1 != n2:
            check(n1, n2)
            if good == True:
                break
        if good == True:
            break
    if good == True:
        break
                    
if good == False or num < 5:
    print ("no")
else:
    print ("yes")

