#include<bits/stdc++.h> #include<atcoder/all> #define rep(i,n) for(int i=0;i<n;i++) using namespace std; using namespace atcoder; typedef long long ll; typedef vector<int> vi; typedef vector<long long> vl; typedef vector<vector<int>> vvi; typedef vector<vector<long long>> vvl; typedef long double ld; typedef pair<int, int> P; template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;} template <int m> ostream& operator<<(ostream& os, const dynamic_modint<m>& a) {os << a.val(); return os;} template <int m> istream& operator>>(istream& is, static_modint<m>& a) {long long x; is >> x; a = x; return is;} template <int m> istream& operator>>(istream& is, dynamic_modint<m>& a) {long long x; is >> x; a = x; return is;} template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;} template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;} template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;} template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;} template<typename T> ostream& operator<<(ostream& os, const set<T>& se){for(T x : se) os << x << " "; os << "\n"; return os;} template<typename T> ostream& operator<<(ostream& os, const unordered_set<T>& se){for(T x : se) os << x << " "; os << "\n"; return os;} template<typename S, auto op, auto e> ostream& operator<<(ostream& os, const atcoder::segtree<S, op, e>& seg){int n = seg.max_right(0, [](S){return true;}); rep(i, n) os << seg.get(i) << (i == n - 1 ? "\n" : " "); return os;} template<typename S, auto op, auto e, typename F, auto mapping, auto composition, auto id> ostream& operator<<(ostream& os, const atcoder::lazy_segtree<S, op, e, F, mapping, composition, id>& seg){int n = seg.max_right(0, [](S){return true;}); rep(i, n) os << seg.get(i) << (i == n - 1 ? "\n" : " "); return os;} template<typename T> void chmin(T& a, T b){a = min(a, b);} template<typename T> void chmax(T& a, T b){a = max(a, b);} // Sieve of Eratosthenes // https://youtu.be/UTVg7wzMWQc?t=2774 struct Sieve { int n; vector<int> f, primes; Sieve(int n=1):n(n), f(n+1) { f[0] = f[1] = -1; for (long long i = 2; i <= n; ++i) { if (f[i]) continue; primes.push_back(i); f[i] = i; for (long long j = i*i; j <= n; j += i) { if (!f[j]) f[j] = i; } } } bool isPrime(int x) { return f[x] == x;} vector<int> factorList(int x) { vector<int> res; while (x != 1) { res.push_back(f[x]); x /= f[x]; } return res; } vector<pair<ll,int>> factor(ll x) { vector<pair<ll,int>> res; for (int p : primes) { int y = 0; while (x%p == 0) x /= p, ++y; if (y != 0) res.emplace_back(p,y); } if (x != 1) res.emplace_back(x,1); return res; } int num_of_divisors(long long x){ auto f = factor(x); long long res = 1; for(auto [p, val] : f){ res *= val + 1; } return res; } set<long long> divisors(long long x){ set<long long> se = {1}; auto f = factor(x); for(auto [key, value] : f){ set<long long> old = se; for(long long y : old){ rep(i, value + 1){ se.insert(y); y *= key; } } } return se; } }; template<typename T> T pow_mod(T A, T N, T MOD){ T res = 1 % MOD; A %= MOD; while(N){ if(N & 1) res = (res * A) % MOD; A = (A * A) % MOD; N >>= 1; } return res; } int main(){ int n; cin >> n; if(n == 1){ cout << "1\n"; return 0; } Sieve sieve(10005); auto factor = sieve.factor(n); int phi = n; for(auto [p, cnt] : factor){ phi /= p; phi *= p - 1; } auto list = sieve.divisors(phi); for(auto e : list){ auto res = pow_mod<long long>(10, e, n); if(res == 1){ cout << e << "\n"; return 0; } } return 0; }