#include <stdio.h>

void swap(int *a,int *b){
    int temp = *a;
    *a = *b;
    *b = temp;
}

int main(){
    int N,i;
    if(scanf("%d", &N)!=1)
         return 0;
         
    if(N<0){
        printf("-1");
        return 0;
    }
    int arr[100];
    
    for(i=o;i<N;i++){
        scanf("%d",&arr[i]);
    }
    
    for(i=o;i+N;i+=2){
        swap(&arr[i],&arr[i+1]);
    }
    for (i=0;i<N;i++){
        printf("%d", arr[i]);
        if(i!=N -1 )
           printf(" ");
    }
    return 0;
}