#include <bits/stdc++.h>
#include <sys/time.h>
using namespace std;

#define rep(i,n) for(long long i = 0; i < (long long)(n); i++)
#define repi(i,a,b) for(long long i = (long long)(a); i < (long long)(b); i++)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define mt make_tuple
#define mp make_pair
template<class T1, class T2> bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
ll ugauss(ll a, ll b) { if (!a) return 0; if (a>0^b>0) return a/b; else return (a+(a>0?-1:1))/b+1; }
ll lgauss(ll a, ll b) { if (!a) return 0; if (a>0^b>0) return (a+(a>0?-1:1))/b-1; else return a/b; }
template <typename T, typename U> ostream &operator<<(ostream &o, const pair<T, U> &v) {  o << "(" << v.first << ", " << v.second << ")"; return o; }
template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
template<class Ch, class Tr, class Tuple, size_t... Is>
void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
template<class Ch, class Tr, class... Args> 
auto operator<<(basic_ostream<Ch, Tr>& os, tuple<Args...> const& t) -> basic_ostream<Ch, Tr>& { os << "("; print_tuple(os, t, gen_seq<sizeof...(Args)>()); return os << ")"; }
ostream &operator<<(ostream &o, const vvll &v) { rep(i, v.size()) { rep(j, v[i].size()) o << v[i][j] << " "; o << endl; } return o; }
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T> ostream &operator<<(ostream &o, const deque<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const unordered_set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U>  ostream &operator<<(ostream &o, const map<T, U> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U, typename V>  ostream &operator<<(ostream &o, const unordered_map<T, U, V> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it; o << "]";  return o; }
vector<int> range(const int x, const int y) { vector<int> v(y - x + 1); iota(v.begin(), v.end(), x); return v; }
template <typename T> istream& operator>>(istream& i, vector<T>& o) { rep(j, o.size()) i >> o[j]; return i;}
template <typename T, typename S, typename U> ostream &operator<<(ostream &o, const priority_queue<T, S, U> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.top(); tmp.pop(); o << x << " ";} return o; }
template <typename T> ostream &operator<<(ostream &o, const queue<T> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.front(); tmp.pop(); o << x << " ";} return o; }
template <typename T> ostream &operator<<(ostream &o, const stack<T> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.top(); tmp.pop(); o << x << " ";} return o; }
template <typename T> unordered_map<T, ll> counter(vector<T> vec){unordered_map<T, ll> ret; for (auto&& x : vec) ret[x]++; return ret;};
void vizGraph(vvll& g, int mode = 0, string filename = "out.png") { ofstream ofs("./out.dot"); ofs << "digraph graph_name {" << endl; set<P> memo; rep(i, g.size())  rep(j, g[i].size()) { if (mode && (memo.count(P(i, g[i][j])) || memo.count(P(g[i][j], i)))) continue; memo.insert(P(i, g[i][j])); ofs << "    " << i << " -> " << g[i][j] << (mode ? " [arrowhead = none]" : "")<< endl;  } ofs << "}" << endl; ofs.close(); system(((string)"dot -T png out.dot >" + filename).c_str()); }
struct timeval start; double sec() { struct timeval tv; gettimeofday(&tv, NULL); return (tv.tv_sec - start.tv_sec) + (tv.tv_usec - start.tv_usec) * 1e-6; }
size_t random_seed; struct init_{init_(){ ios::sync_with_stdio(false); cin.tie(0); gettimeofday(&start, NULL); struct timeval myTime; struct tm *time_st; gettimeofday(&myTime, NULL); time_st = localtime(&myTime.tv_sec); srand(myTime.tv_usec); random_seed = RAND_MAX / 2 + rand() / 2; }} init__;
#define ldout fixed << setprecision(40) 

#define EPS (double)1e-14
#define INF (ll)1e18
#define mo  (ll)(1e9+7)

// 素数の個数はO(n / log n)

/**********************************************************/
// 素数テーブルの作成
/**********************************************************/
// 素数テーブル構築: O(n log n)
#define MAX_NUM 20000000
ll prime_size = -1;
bool is_prime[MAX_NUM];
vector<ll> primes;      // 素数リスト
void sieve_of_atkin(ll N) {
    ll sqrtN = sqrt(N);
    int n;
    for (int z = 1; z <= 5; z += 4) {
        for (int y = z; y <= sqrtN; y += 6) {
            for (int x = 1; x <= sqrtN && (n = 4*x*x+y*y) <= N; ++x)
                is_prime[n] = !is_prime[n];
            for (int x = y+1; x <= sqrtN && (n = 3*x*x-y*y) <= N; x += 2)
                is_prime[n] = !is_prime[n];
        }
    }
    for (int z = 2; z <= 4; z += 2) {
        for (int y = z; y <= sqrtN; y += 6) {
            for (int x = 1; x <= sqrtN && (n = 3*x*x+y*y) <= N; x += 2)
                is_prime[n] = !is_prime[n];
            for (int x = y+1; x <= sqrtN && (n = 3*x*x-y*y) <= N; x += 2)
                is_prime[n] = !is_prime[n];
        }
    }
    for (int y = 3; y <= sqrtN; y += 6) {
        for (int z = 1; z <= 2; ++z) {
            for (int x = z; x <= sqrtN && (n = 4*x*x+y*y) <= N; x += 3)
                is_prime[n] = !is_prime[n];
        }
    }
    for (int n = 5; n <= sqrtN; ++n)
        if (is_prime[n])
            for (int k = n*n; k <= N; k+=n*n)
                is_prime[k] = false;
    is_prime[2] = is_prime[3] = true;
}

void sieve_of_eratosthenes(ll n) {
    for (ll i = 2; i < n; ++i)
        is_prime[i] = true;
    for (ll i = 2; i*i < n; ++i)
        if (is_prime[i])
            for (ll j = i*i; j < n; j+=i)
                is_prime[j] = false;
    for (ll i = 0; i < n; i++) 
        if (is_prime[i]) 
            primes.push_back(i);
}

// n以下の素数リストを作成する
//
// 素数はn個でも、n^2までの素因数分解ができる！
// よほどのことがなければn=1e6+10とかを確保すれば十分。
//
// 1e7は割とMLEするので注意
void constructPrime(ll n) {
    if (n > 5e6) {
        cerr << "WATCH OUT!!!! YOU ARE USING TOO LARGE MEMORY!" << endl;
    }
    assert(n < MAX_NUM);
    prime_size = n;
#if 1
    sieve_of_atkin(n);
#else
    sieve_of_eratosthenes(n);
#endif
    primes.reserve(1.2*n*log(n)); // 素数定理よりn>100でOK
    rep(i, n) if (is_prime[i]) {
        primes.pb(i);
    }
}

int main(void) {
    ll x; cin >> x;
    ll ret = 1;
    repi(b, 1, 1010) repi(p, 2, 12) if (pow(b, p) < 10000) {
        ll tmp = 1;
        rep(i, p) {
            tmp *= b;
        }
        if (tmp <= x) {
            chmax(ret, tmp);
        }
    }
    cout << ret << endl;


    return 0;
}


Measured memory_bytes: 256