n = int(input())
s = input()
slen = len(s)
result = 0

possiblepatios = []

curr = 3
while True:
    if curr ** 2 <= slen:
        possiblepatios.append(curr**2)
    else:
        break
    curr += 1

for pp in possiblepatios:
    start = 0
    end = pp - 1
    cx = s[start:end+1].count('X')
    co = s[start:end+1].count('O')
    #print(pp, start, end, cx, co)
    while end < slen:
        side = int(pp ** (1/2))
        inner = (side-2)**2
        if inner == co or inner == cx:
            result += 1
        if s[start] == "O":
            co -= 1
        else:
            cx -= 1
        start+=1
        if end + 1 == slen:
            break
        end+=1
        if s[end] == "O":
            co += 1
        else:
            cx += 1
print(result)