#include <fstream>
#include <cmath>
using namespace std;

int main()
{
    fstream iof{ "input.txt", ios::in };
    unsigned N;
    iof >> N;
    iof.close();

    unsigned maxpot = 1, maxbase = sqrt(N);
    for (unsigned M = 2; M <= maxbase; M++)
    {
        unsigned pot = M * M;
        while(pot * M <= N)
            pot *= M;
        if (pot > maxpot)
            maxpot = pot;
        if (pot == N) break;
    }

    iof.open("output.txt", ios::out);
    iof << maxpot;
    iof.close();
    return 0;
}