#include <iostream>
using namespace std;

int main()
{
    int n;
    cout<<"enter the number of elements in the array ";
    cin>>n;

    int a[n];

    for (int i = 0; i < n; i++) {
        cin>>a[i];
    }

   for (int i = 1; i < n; i += 2)
    {
        int t = a[i-1];
        a[i-1] = a[i];
        a[i] = t;
    }

   for (int i = 0; i < n; i++){
      cout << " " << a[i];
   }

   cout << endl;

   return 0;
}