#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#define rep(i,n) for(int i = 0;i < n;i++)
#define REP(i,n,k) for(int i = n;i < k;i++)
#define P(p) cout<<(p)<<endl;
#define pi 3.1415926535
using namespace std;
typedef long long ll;
int dx[] = { 0, 1, 0, -1 };
int dy[] = { -1, 0, 1, 0 };

unsigned long long sttoi(std::string str) {
	unsigned long long ret;
	std::stringstream ss; ss << str;
	ss >> ret;
	return ret;
}

ll modpow(ll x, ll k, ll m){
	if (k == 0){
		return 1;
	}
	if (k % 2 == 0){
		return modpow(x*x % m, k / 2, m);
	}
	else{
		return modpow(x, k - 1, m)*x % m;
	}
}

bool isPrime(int n){
	for (int i = 3; i*i <= n; i += 2){
		if (n%i == 0)return false;
	}
	return true;
}

bool isPrime(ll n, ll k){
	if (n == 1 || n % 2 == 0){
		return false;
	}
	ll d = n - 1;
	ll s = 0;
	while (d % 2 == 0){
		d = d / 2;
		s++;
	}

	for (int i = 0; i < k; i++) {
		bool isPP = false;
		ll a = round((n - 2) * rand()) + 1;
		ll r = modpow(a, d, n);
		if (r == 1 || r == n - 1) {
			isPP = true;
		}
		for (int j = 0; j < s; j++) {
			r = modpow(r, 2, n);
			if (r == n - 1) {
				isPP = true;
			}
		}
		if (!isPP) {
			return false;
		}
	}
	return true;
}



void solve() {
	ll n;
	cin >> n;
	if (n / 100000000 > 0){
		if (isPrime(n, 50)){
			P(n);
		}
		else{
			for (int i = 3; i*i <= n; i++){
				if (n%i == 0){
					P(i);
					return;
				}
			}
		}
	}
	else{
		if (isPrime(n)){
			P(n);
		}
		else{
			for (int i = 3; i*i <= n; i++){
				if (n%i == 0){
					P(i);
					return;
				}
			}
		}
	}
}

int main() {
	solve();
	return 0;
}