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

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))

bool isPrime(int N) {
	if (N == 2 || N == 3) return true;
	for (int i = 2; i * i <= N; i++) if (N % i == 0) return false;
	return true;
}
int main() {
	int N; cin >> N;
	
	while (isPrime(N)) {
		N++;
	}
	cout << N << endl;
}