#include<iostream>
#include<cstdio>
using namespace std;
int main(){
int x;
cin>>x;
if(x%3==0)printf("%d",3); 
if(x%5==0)printf("%2d",5);
if(x%7==0)printf("%2d",7);
if((x%3)&&(x%5)&&(x%7)!=0) cout<<"n"<<endl;
return 0;
}