import math

def f(m, n):
    def f1(i,r):
        while i>2:
            if n%i==0:
                r=i
            i=i-1
        return r
    f2 = lambda i: i//2 if i!=4 and n%2==0 else i
    r = f1(m,0)
    return f2(n) if r==0 else r

g = lambda n: math.floor(math.sqrt(n))

h = lambda n: f(g(n),n)

print(h(int(input())))