文件目录

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    for (int i = 2; i <= n; i += 2)
        cout << i << " ";
    return 0;
}
int ans1()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        if (i % 2 == 0)
            cout << i << " ";
    return 0;
}