This problem is very easy to solve.
You may be very tired during this contest. So we prepared a gift for you.
You just copy and paste this code and you will get AC!
Ctrl + C && Ctrl + V is a necessary skill for a programming ape.
#include<iostream>
using namespace std;
const long long mod = 1e9+7;
long long func(int x){
if (x==1||x==0){
return 1;
}
return (x*func(x-1)+(x-1)*func(x-2)) % mod;
}
int n;
int main(){
cin>>n;
cout<<func(n);
return 0;
}