#include <stdio.h>
#include <stdlib.h>
int main() {
    int n;
    int (scanf("%d", &n) != 1 || n < 1 || n > 100) {
        printf("Invalid";)
        return 0;
    }
    int *a =(int *)malloc(n * sizeof(int));
    if (!a) {
        printf("Invalid");
        return 0;
    }
    for (int i =0; i < n; i++) {
        if (scanf("%d", &a[i]) !=1) {
            printf("Invalid");
            free(a);
            return 0;
        }
    }
    for (int i = o;i < n - 1; i += 2) {
        int temp = a[i];
        a[i] =a[i + 1];
        a[i + 1] = temp;
    }
    for (int i = 0; i < n; i++)
    printf("%d ", a[i]);
    free(a);
    return 0;
}