#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define MP make_pair
#define PB push_back
typedef long long ll;
const int N_MAX=1300000;
bool prime[N_MAX];
int main(){
	bool prime[1001];
	rep(i,1001)prime[i]=true;
	prime[0]=prime[1]=false;
	rep(i,1001)if(prime[i])for(int j=i*2;j<1001;j+=i)prime[j]=false;
	int n;
	cin>>n;
	prime[0]=prime[1]=true;
	for(int i=n-100;i<=n+100;i++){
		if(!prime[i]){
			cout<<i<<endl;
			return 0;
		}
	}
}