n = int(input())
lst = [0] * n
if n % 2 != 0:
print("-1")
else:
for i in range(0, n):
if i % 2 == 0:
lst[i+1] = i + 1
else:
lst[i-1] = i + 1
finLst = [str(x) for x in lst]
print(" ".join(finLst))
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin >> n;
int a[n];
for (int i = 1; i <= n; i++)
{
a[i] = i;
}
if (n % 2 != 0)
cout << "-1" << endl;
else
{
for (int i = 1; i <= n-1; i += 2)
{
swap(a[i], a[i+1]);
}
for (int i = 1; i <= n; i++)
{
cout << a[i] << " ";
}
}
return 0;
}454A - Little Pony and Crystal Mine | 2A - Winner |
1622B - Berland Music | 1139B - Chocolates |
1371A - Magical Sticks | 1253A - Single Push |
706B - Interesting drink | 1265A - Beautiful String |
214A - System of Equations | 287A - IQ Test |
1108A - Two distinct points | 1064A - Make a triangle |
1245C - Constanze's Machine | 1005A - Tanya and Stairways |
1663F - In Every Generation | 1108B - Divisors of Two Integers |
1175A - From Hero to Zero | 1141A - Game 23 |
1401B - Ternary Sequence | 598A - Tricky Sum |
519A - A and B and Chess | 725B - Food on the Plane |
154B - Colliders | 127B - Canvas Frames |
107B - Basketball Team | 245A - System Administrator |
698A - Vacations | 1216B - Shooting |
368B - Sereja and Suffixes | 1665C - Tree Infection |