n = int(input())
e = int(input())

if e == 0 or n == 0:
	print(0)
	exit()

if (n % (5 ** e) == 0):
	print(0)
	exit()

ee = e
nn = n
basis = 1
while n % 25 == 0:
	n //= 25
	e -= 2
	basis *= 5

if not (n % 5 == 1 or n % 5 == 4):
	print("NaN")
	exit()

a = -1
for i in range(5):
	if (i * i - n) % 5 == 0:
		a = i
		break

assert a >= 0

for t in range(2, e+1):
	c = (a * a - n) // (5 ** (t-1))
	y = -1
	for yy in range(5):
		if (2 * a * yy + c) % 5 == 0:
			y = yy
			break
	assert y >= 0
	b = (a + 5 ** (t-1) * y) % (5 ** t)
	a = b

a *= basis
a %= (5 ** ee)
if a > 2 ** 29:
	a -= 5 ** ee

if a < -2 ** 29:
	print("NaN")
	exit()

print(a)
#print((a * a - nn) % (5 ** ee) == 0)