import math

num_letters = int(input())
letters = input()

i=3
combinations = 0
while i**2 <= num_letters:
    count_x = 0
    count_0 = 0
    for j in range(i**2):
        if letters[j] == "X":
            count_x += 1
        else:
            count_0 += 1
    
    j = 0
    while i**2 + j <= num_letters:
        smaller = count_x if count_x < count_0 else count_0
        bigger = count_0 if count_0 > count_x else count_x
        if (4*math.sqrt(smaller)+4==bigger):
            combinations += 1
        j += 1
        if i**2 + j > num_letters:
            break
        if letters[j-1] == "X":
            count_x -= 1
        else:
            count_0 -= 1
        if letters[i**2+j-1] == "X":
            count_x += 1
        else:
            count_0 += 1
    i+=1

print(combinations)