暴力枚举AC

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