题解在此

#include <iostream>
using namespace std;
int main(){
    int a;
    cin>>a;
    if (a%105==0){
        cout<<"3 5 7";
    }else if (a%15==0){
        cout<<"3 5";        
    }else if (a%35==0){
        cout<<"5 7";
    }else if (a%21==0){
        cout<<"3 7";
    }else if (a%3==0&&a%35!=0){
        cout<<"3"; 
    }else if (a%5==0&&a%21!=0){
        cout<<"5"; 
    }else if (a%7==0&&a%15!=0){
        cout<<"7"; 
    }else{
        cout<<"n";
    }
    return 0;
}