#include <bits/stdc++.h>

using namespace std;

const int CBRT = 3.5e7, MX = 3.6e7, OFFSET = 1e6;
const long long MXN = 2.6e18;
const double pi = acos(-1);

int u[MX], M[MX];
vector<int> primes;

void precalc() {
	u[0] = M[0] = 0;
	u[1] = M[1] = 1;
	
	vector<int> lp(MX, 0);
	for (int i = 2; i < MX; i++) {
		if (lp[i] == 0) {
			primes.push_back(i);
			lp[i] = i;
			u[i] = -1;
		}
		
		for (int p : primes) {
			if (p * i >= MX) break;
			lp[p * i] = p;
			if (lp[i] == p) break;
			u[p * i] = -1 * u[i];
		}
		
		M[i] = M[i - 1] + u[i];
	}
}

long long f(long long n) {
	static int dp[MXN / CBRT / CBRT];
	
	long long res = 0;
	for (int d = 1; d < CBRT; d++) res += u[d] * (n / d / d);
	res -= M[CBRT - 1] * (n / CBRT / CBRT);

	int val = 0;
	while (CBRT * (val + 1ll) * CBRT <= n) val++;
	
	while (val > 0) {
		int x = sqrt(n / val);
		while (n / x / x < val) x--;
		while (n / (x + 1) / (x + 1) == val) x++;
		
		dp[val] = 1;
		
		int g = x / MX + 1, l = 2;
		for (int r; l < g; l = r + 1) {
			int v = x / l;
			r = x / v;
			dp[val] -= (r - l + 1) * dp[val * l * l];
		}
		
		for (int r; l <= x; l = r + 1) {
			int v = x / l;
			r = x / v;
			dp[val] -= (r - l + 1) * M[v];
		}
		
		res += dp[val];
		
		val--;
	}

	return res;
}

int main() {
	precalc();
	
	long long n;
	ignore = scanf("%lld", &n);
	
	long long x = max(n / (1 - 6 / (pi * pi)) - OFFSET, 0.0);
	n -= x - f(x);
	assert(n > 0);
	
	static long long a[2 * OFFSET];
	iota(a, a + 2 * OFFSET, x + 1);
	
	for (int d : primes) {
		if (d * d * d > x + 2 * OFFSET) break;
		for (int i = d - (x % d) - 1; i < 2 * OFFSET; i += d) {
			int cnt = 0;
			while (a[i] > 0 && a[i] % d == 0) {
				a[i] /= d;
				cnt++;
			}
			
			if (cnt > 1) a[i] = 0;
		}
	}
	
	for (int i = 0; i < 2 * OFFSET; i++) {
		long long y = sqrt(a[i]);
		while (y * y > a[i]) y--;
		while ((y + 1) * (y + 1) <= a[i]) y++;
		
		if (y * y == a[i] && a[i] != 1) n--;
		if (n == 0) {
			printf("%lld\n", x + 1 + i);
			return 0;
		}
	}
	
	assert(false);
	
	return 0;
}