#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

const int mod = 1000000007;
const int INF = (int)1e9;
const ll LLINF = (ll)2e18;
const double PI = 3.1415926536;

const int SIZE = 1000;

const int MAX_P = 1010;
bool prime[MAX_P+1];
void primen(void){
    for(int i=2;i<=MAX_P;i++)
        prime[i]=true;
    
    for(int i=2;i*i<=MAX_P;i++)
        if(prime[i])
            for(int j=i;i*j<=MAX_P;j++)
                prime[i*j]=false;
    
}

int main(){
    int a;
    
    scanf("%d",&a);
    
    primen();
    
    for(int i=max(a-100,4);i<=a+100;i++){
        if(!prime[i]){
            printf("%d\n",i);
            return 0;
        }
    }
    
    return 0;
}