132_exp

#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define el endl
#define umi unordered_map<int, int>
#define umll unordered_map<ll, ll>
#define all(vect) vect.begin(), vect.end()
#define reset(A, x) memset(A, x, sizeof(A))
#define approx(n) fixed << setprecision(n)

using namespace std;

const int mod = 1e9 + 7;

int log_a_to_base_b(int a, int b)
{
  return int(log2(a) / log2(b));
}

void solve() {
  int n;
  cin >> n;
  int maxx = 0;
  for(int i = 2; i < n; i++) {
    int te = log_a_to_base_b(n, i);
    int p = pow(i, te);
    if(p > maxx && p <= n) {
      maxx = p;
    }
  }
  cout << maxx << el;
}

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

  int t = 1;
  // cin >> t;
  // cin.ignore();
  while (t--) {
    solve();
  }
  return 0;
}

/*

*/