from math import gcd
from itertools import permutations

def totatives(n):
    phi = int(n > 1 and n)
    for p in range(2, int(n ** .5) + 1):
        if not n % p:
            phi -= phi // p
            while not n % p:
                n //= p
    #if n is > 1 it means it is prime
    if n > 1: phi -= phi // n 
    return phi

def permute(num,phi_num):
    temp="".join(sorted(str(num)))
    phi_num="".join(sorted(str(phi_num)))
    return temp==phi_num

N=int(input())
d={}
for n in range(12,N):
    if permute(n,totatives(n)):
        #print(permute,phi(n))
        d[n]=(n/totatives(n))
    
#print(d)
min_b=min(d.values())
for a,b in d.items():
    if b==min_b:
        print(a)
        break