#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
cin >> n;
bool found =false ;
for (int i=1; i<=n; i++)
{
if (i%2==0)
{
cout << i << endl;
found = true;
}
}
if (!found) {
cout << "-1" << endl;
}
}
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