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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
import math

segment_count = int(input())

segment = input()

max_gap = math.floor(segment_count / 5)
can_solve = False
if max_gap < 1:
    print('no')
else:
    first_star = -1
    for index, seg in enumerate(segment):
        if seg == '*':
            first_star = index
            break
    if first_star == -1:
        print('no')
    else:
        for i in range(max_gap,0,-1):
            is_solution = False
            for x in range(5):

                if segment[first_star + (x * i)] != '*':
                    break
                elif x == 4:
                    is_solution = True
                    break
            if is_solution == True:
                can_solve = True
                break
    if can_solve == True:
        print('yes')
    else:
        print('no')
