#include <iostream>     // Input/output stream objects
#include <fstream>      // File stream objects
#include <sstream>      // String stream objects
#include <iomanip>      // Input/output manipulators
#include <string>       // String class and functions
#include <vector>       // Dynamic array
#include <list>         // Doubly linked list
#include <set>          // Set container
#include <map>          // Map container
#include <queue>        // Queue container
#include <stack>        // Stack container
#include <algorithm>    // Algorithms on sequences (e.g., sort, find)
#include <cmath>        // Mathematical functions
#include <climits>      // LLONG_MAX, LLONG_MIN
#include <ctime>        // Date and time functions
#include <cstdlib>      // General purpose functions (e.g., memory management)
#include <cstring>      // C-style string functions
#include <cctype>       // Character classification functions
#include <cassert>      // Assert function for debugging
#include <exception>    // Standard exceptions
#include <functional>   // Function objects
#include <iterator>     // Iterator classes
#include <limits>       // Numeric limits
#include <locale>       // Localization and internationalization
#include <numeric>      // Numeric operations (e.g., accumulate)
#include <random>       // Random number generators
#include <stdexcept>    // Standard exception classes
#include <typeinfo>     // Runtime type information
#include <utility>      // Utility components (e.g., std::pair)
#include <bitset>

using namespace std;

#define FOR(i, a, b) for(int i = a; i < (b); i++)
#define FORE(i, a, b) for(int i = a; i <= (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
#define x first 
#define y second
#define mp make_pair
#define PI 3.141592653
#define compress(coord) sort(all(coord)), coord.resize(unique(all(coord)) - coord.begin())
const double eps = 1e-9; // x < eps (x <= 0) x < -eps (x < 0)

const int N = 1e6 + 10;
vector<ll> numpow(N, 1), check(N), prime;
double k, inf = 1e18;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

    cin >> k;
    if (k == 1) {
        cout << 1 << endl;
        return 0;
    }

    FOR(i, 2, N) if (!check[i]) {
        prime.push_back(i);
        for (int j = i; j < N; j += i) {
            check[j] = true;
            int temp = j, cnt = 0;
            while (temp % i == 0) {
                cnt++;
                temp /= i;
            }
            numpow[j] *= (ll)(cnt + 1);
        }
    }

    for (ll i = 2; i < N; i++) {
        ll curpow = 1;
        bool of = false;
        FOR (j, 0, numpow[i]) {
            if (inf / i >= curpow)  curpow *= i;
            else {
                of = true;
                break;
            }
        }

        if (!of && curpow == k) {
            cout << i << endl;
            return 0;
        }
    }

    ll sq = (ll)sqrt(k);

    if (sq * sq == (ll)k) {
        for (ll pp : prime) if (sq % pp == 0) {
            cout << -1 << endl;
            return 0;
        } 
        cout << sq << endl;
        return 0;
    }

    cout << -1 << endl;
    return 0;
}