#include <iostream>
using namespace std;

// function check whether a number
// is prime or not
bool isPrime(long long n)
{
    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;

    for (long long i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;

    return true;
}

// Function to prlong long primes
void Prime(long long n)
{
    for (long long i = 2; i <= n; i++) {
        if (isPrime(i) && n % i == 0)
        {
            cout << i;
            return;
        }
    }
}
// Driver Code
int main()
{
    long long n;
    cin >> n;
    Prime(n);
    return 0;
}