#include <cstdio>

bool isNotPrime[1101];

int main(){
    isNotPrime[1] = true;

    for(int i=4;i<=1100;i+=2){
        isNotPrime[i] = true;
    }

    for(int i=3;i<=1100;i+=2){
        if(!isNotPrime[i]){
            for(int j=2*i;j<=1100;j+=i){
                isNotPrime[j] = true;
            }
        }
    }

    int N;
    scanf("%d", &N);

    for(int i=N-100;i<=N+100;i++){
        if(i == 1){continue;}
        if(!isNotPrime[i]){continue;}
        printf("%d\n", i);
        return 0;
    }
}