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

#define For(i, a, b) for(int i = (a); i < (b); i++)
#define rep(i, n) For(i, 0, n)
#define rFor(i, a, b) for(int i = (a); i >= (b); i--)
#define ALL(v) (v).begin(), (v).end()
#define rALL(v) (v).rbegin(), (v).rend()

using lint = long long;
using ld = long double;

int INF = 2000000000;
lint LINF = 1000000000000000000;

struct SetupIo {
    SetupIo() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
        cout << fixed << setprecision(15);
    }
} setupio;

unsigned long long KthRootFloor(unsigned long long a, unsigned long long k) {
    assert (k != 0);
    using ulint = unsigned long long;
    if (a == 0 || a == 1 || k == 1) {
        return a;
    }
    if (k >= 64) {
        return 1;
    }
    auto ok = [&](ulint x) -> bool {
        ulint cur = 1;
        for (int i = 0; i < k; i++) {
            if (a / cur < x) {
                return false;
            }
            cur *= x;
        }
        return cur <= a;
    };
    ulint l = 0, r = a;
    while (r - l > 1) {
        ulint mid = (l + r) / 2;
        if (ok(mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    return l;
}

int main() {
    using ulint = unsigned long long;
    ulint n;
    cin >> n;
    cout << KthRootFloor(n, 2) << "\n";
}