#include <iostream>
#include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    srand(time(NULL));
    for (int i = 0; i < n; i++)
        a[i] = rand() % 1000;
    for (int i = 1; i < n; i+=2)
        swap(a[i], a[i-1]);
    for (int i : a)
        cout << i << " ";

    return 0;
}