#include<bits/stdc++.h>

using namespace std;

typedef long long int ll;
typedef long double ld;
#define f first
#define s second
#define pb push_back
#define pii pair<int, int>


const int N = 1e5 + 100;
const int inf = 1e9;
const ll mod =  9302023;



int main()
{

        ll x;
        cin >> x;
        for (int i = 1; i <= 1000; i++) {
                int cnt = 0;
                for (int f = 1; f * f <= i; f++) {
                        if (i % f == 0) {
                                cnt++;
                                if (i / f != f) {
                                        cnt++;
                                }
                        }
                }
                __int128 p = 1;
                for (int j = 0; j < cnt; j++) {
                        p *= i;
                        if (p > 1e18) {
                                break;
                        }
                }
                if (p == x) {
                        cout << i << endl;
                        return 0;
                }
        }
                cout << -1 << endl;

    return 0;
}