#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

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

    vector<bool> is_p(2000, true);
    for(int i=2; i<2000; ++i){
        if(!is_p[i]) continue;
        for(int j=i+i; j<2000; j+=i){
            is_p[j] = false;
        } 
    }

    for(int ans = N-100; ans <= N+100; ++ans){
        if(!is_p[ans]){
            cout << ans << endl;
            return 0;
        }
    }
}