#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int, int> P;


int main()
{
	int n;
	cin >> n;

	bool s[1300];
	for (int i = 0; i < 1200; i++) {
		s[i] = true;
	}

	for (int i = 2; i*i < 1200; i++) {
		int tmp = i;
		while (true) {
			tmp *= i;
			if (tmp>=1200) {
				break;
			}
			s[tmp] = false;
		}
	}
	int ret;
	for (int i = n-100; i <= n+100; i++) {
		if (!s[i]) {
			ret = i;
			break;
		}
	}
	cout << ret << endl;

}