n = int(raw_input())
l = []
if n % 2 == 0 and n/2 >= 3:
    l.append(n/2)
if n % 4 == 0:
    l.append(4)
d = 3
while d * d <= n:
    if n % d == 0:
        l.append(d)
        l.append(n/d)
        break
    d += 2
if l != []:
    l.sort()
    print l[0]
else:
    print n