#include<stdio.h>
long long int pow(long long int a, long long int n)
{
	long long int res = 1;
	while (n > 0)
	{
		if (n % 2 > 0)
			res = res * a;
		a = a * a;
		n /= 2;
	}
	return res;
}
long long int root(long long int a, long long int n)
{
	long long int min, mid, max;
	min = 0;
	max = 1;
	if (n == 2)
	{
		while (pow(max, n) < a)
			max *= 2;
	}
	else
	{
		while (pow(max, n) < a)
			max++;
	}
	while (max - min > 1)
	{
		mid = (max + min) / 2;
		if (pow(mid, n) < a)
			min = mid;
		else
			max = mid;
	}
	return max;
}
int main()
{
	long long int a;
	scanf("%lld", &a);
	long long int i, ans = a, r;
	for (i = 2;; i++)
	{
		r = root(a, i);
		if (ans > r * i)
			ans = r * i;
		if (r == 2)
			break;
	}
	printf("%lld\n", ans);
	return 0;
}