to find the largest prime factor of a number

n = int(input())
x = []
p = []
for i in range(2, n):
    if n % i == 0:
        x.append(i)
x.sort()
for k in x:
    for a in range(2, k + 1):
        if k % a == 0:
            break
        else:
            p.append(k)
            p.append(2)
p.sort()
u = list(set(p))
print(p[-1])