#!/usr/bin/env python3

nums = int(input())
file = input().strip()


blue = [0] * nums
red = [0] * nums
blue_cnt = 0
red_cnt = 0

for i in range(nums):
    if file[i] == 'X':
        blue_cnt += 1
    else:
        red_cnt += 1
    blue[i] = blue_cnt
    red[i] = red_cnt

#print(blue, red)

def check_tiles(b, r):
    if b + r < 9:
        return False
    if b % 4 == 0:
        n = b // 4 - 1
        if r == n * n:
            return True
    if r % 4 == 0:
        n = r // 4 - 1
        if b == n * n:
            return True
    return False

blue = [0] + blue
red = [0] + red

cnt = 0
for i in range(nums - 8):
    #print("Here")
    for k in range(3, nums + 1):
        j = i + k*k
        #print(i, j)
        #input()
        if j >= len(red):
            break
        r = red[j] - red[i]
        b = blue[j] - blue[i]
        #print(i, j, b, r)
        #input()

        if check_tiles(b, r):
            cnt += 1

print(cnt)