#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using namespace std;


int main()
{
    long long a;
    cin >> a;
    vector<long long> v;
    if (a < 7) cout << a << endl;
    else if (a <= 9) cout << 6 << endl;
    else if (a <= 16) cout << 8 << endl;
    else {
        for (int i = 3; i < 120; i++){
            for (int j = 2; j < 60; j++){
                if (pow(i, j) >= a) v.push_back(i*j);
            }
        }
        sort(v.begin(), v.end());
        cout << v[0] << endl;
    }
}