def get_prefixes(pattern):
  r = [(0,0),]
  x = 0
  o = 0
  
  for i, c in enumerate(pattern):
    if c == 'X':
      x += 1

    else:
      o += 1

    r.append((x, o))

  return r


def main():
  n = int(input())
  pattern = input()

  prefixes = get_prefixes(pattern)

  res = 0
  i = 3
  while i*i <= n:
    for j in range(0, n - i*i + 1):
      x1, o1 = prefixes[j]
      x2, o2 = prefixes[j + i*i]
      x, o = x2-x1, o2-o1

      if (o == ((i-2)*(i-2)) and x == (i*i - ((i-2)*(i-2)))) or (x == ((i-2)*(i-2)) and o == (i*i - ((i-2)*(i-2)))):
        res += 1

    i += 1

  print(res)


if __name__ == '__main__':
  main()