#include <iostream>
using namespace std;
int main() {
    long long n; cin >> n;
    if (n == 1) { cout << 2 << endl; return 0; }
    long long ans = n-1;
    for (long long p = 2; p * p + p + 1 <= n; p++) {
        for (long long q = 1; q <= n; q = q * p + 1) {
            if (n % q == 0 && n / q < p) {
                ans = min(ans, p);
                break;
            }
        }
    }
    for (long long d = 1; d * (1 + d) < n; d++) {
        if (n % (1 + d) == 0 && n / (1 + d) < d)
            ans = min(ans, d);
    }
    cout << ans << endl;
}