import math input() inp = input().strip() res = 0 for i in range(3, 1 + math.floor(math.sqrt(len(inp)))): arr = inp[0:i ** 2] num_o = arr.count('O') if num_o == (i - 2) ** 2: res += 1 for c in range(len(inp) - (i ** 2)): if inp[c] == 'O': num_o -= 1 if inp[c + (i ** 2)] == 'O': num_o += 1 if num_o == (i - 2) ** 2: res += 1 print(res)