n, b = map(int, input().split())
from math import gcd
if gcd(n, b) != 1:
    print("NaN")
    exit()

def extgcd(a, b):
    if b:
        d, y, x = extgcd(b, a % b)
        y -= (a // b)*x
        return d, x, y
    return a, 1, 0

d, x, y = extgcd(n, b)
if x < 0:
    x += (-x+b) // b * b
else:
    x %= b

x -= 2 * b
while x < 0:
    x += b

print(x)