import math N = int(input()) sieve_limit = int(math.sqrt(N)) prime_factor = [] prime = [] sieve = list(range(2,sieve_limit+1)) j = 0 remainder = N while sieve: factor = sieve[0] prime.append(factor) sieve = [i for i in sieve if i % factor != 0] while remainder % factor == 0: remainder //= factor prime_factor.append(factor) if remainder < factor: break if remainder > 1: prime_factor.append(remainder) totient = N for factor in prime_factor: totient = (totient*(factor-1))//factor prime_factor = [] remainder = totient for factor in prime: exponent = 0 while remainder % factor == 0: remainder //= factor exponent += 1 if exponent > 0: prime_factor.append((factor,exponent)) if remainder == 1: break if remainder > 1: prime_factor.append((remainder,1)) K_candidate = [1] for factor,exponent in prime_factor: K_candidate_new = set() for i in range(exponent+1): K_candidate_new = K_candidate_new | {j*factor**i for j in K_candidate} K_candidate = K_candidate_new K_candidate_list = list(K_candidate) K_candidate_list.sort() for k in K_candidate_list: binary_k = list(map(int, bin(k)[2:])) lenk = len(binary_k) mod_list = [0] * (lenk) mod_list[0] = 10%N for i in range(lenk-1): mod_list[i+1] = mod_list[i]**2 %N r = 1 for i,bit in enumerate(binary_k): if bit: r = r * mod_list[lenk-i-1] % N #print(k,r,mod_list,binary_k) if r == 1: print(k) break if N == 1: print(1)