def gcd(a,b):
    if a>b:
        m=a
        t=b
    else:
        m=b
        t=a
    r=m%t
    while r!=0:
        m=t
        t=r
        r=m%t
    return t
N,D=(int(i)for i in input (). split ())
N//=gcd(N,D)
print (N-1)