为什么还有头文件啊

#include<bits/stdc++.h>
using namespace std;
int main(){
    freopen("apple.in","r",stdin);
 	freopen("apple.out","w",stdout);
    int n; cin >> n;
    int ans = 0;
	int l = 0;
    while(n != 0){
    	if(n % 3 == 1 && l == 0) l = ans + 1;
    	n -= ceil(n / 3.0);
    	ans++;
	}
	cout << ans << " " << l;
 	fclose(stdin);
 	fclose(stdout);
    return 0;
}