import sys import math n = int(input()) tiles = list(sys.stdin.readline().rstrip('\n')) size=3 max_size = int(round(math.sqrt(n),0)) result = 0 for j in range(size, max_size+1): x_count = 0 o_count = 0 for i in range(n): if tiles[i] == 'X': x_count +=1 if tiles[i] == 'O': o_count +=1 if i>=j*j: if tiles[i-j*j] == 'X': x_count -=1 if tiles[i-j*j] == 'O': o_count -=1 if x_count + o_count == j**2: if x_count == j**2-(j-2)**2: result +=1 if o_count == j**2-(j-2)**2: result +=1 print(result)