寒假3.4

One way to create a task is to learn from math. You can generate some random math statement or modify some theorems to get something new and build a new task from that.
For example, there is a statement called the "Goldbach's conjecture". It says: "each even number no less than four can be expressed as the sum of two primes". Let's modify it. How about a statement like that: "each integer no less than 12 can be expressed as the sum of two composite numbers." Not like the Goldbach's conjecture, I can prove this theorem.
You are given an integer n no less than 12, express it as a sum of two composite numbers.
Input
The only line contains an integer n (12 ≤ n ≤ 106).
Output
Output two composite integers x and y (1 < x, y < n) such that x + y = n. If there are multiple solutions, you can output any of them.
Examples
Input
12
Output
4 8
Input
15
Output
6 9
Input
23
Output
8 15
Input
1000000
Output
500000 500000
Note
In the first example, 12 = 4 + 8 and both 4, 8 are composite numbers. You can output "6 6" or "8 4" as well.
In the second example, 15 = 6 + 9. Note that you can't output "1 14" because 1 is not a composite number.
本题相当于哥德巴赫猜想的相反意，为两个非质数相加成为一个数，及判断是非为质数即可。

#include<iostream>
using namespace std;
bool I(int x) {
        for (int i = 2; i*i <= x; ++i)
                if (x%i == 0)return false;
       return true;
   
}
int main() {
        int n; cin >> n;
       for (int i = 4;; i += 2)
        if (!I(n - i)) { cout << i << ' ' << (n - i) << endl; break; }
        return 0;
   
}