_ = input()
vstup = input()
maxr = int(len(vstup)**0.5)
res = 0
for rozmer in range(3, maxr+1):
	ov = (rozmer-2)**2
	xv = (rozmer-1)*4
	vzorne = ((xv, ov), (ov, xv))
	act = {'X': 0, 'O':0}
	plocha = rozmer**2
	subs = vstup[:plocha]
	for z in subs:
		act[z] = act[z] + 1
	if (act['X'], act['O']) in vzorne:
		res += 1
	for w in vstup[plocha:]:
		z = subs[0]
		act[z] = act[z] - 1
		subs = subs[1:] + w
		act[w] = act[w] + 1
		if (act['X'], act['O']) in vzorne:
			res += 1
print(res)