import java.util.*;

public class New {
    private static final Value used=new Value(-1,-1);
    public static void main(String[] args) {
        int offset=0;

        Scanner sc=new Scanner(System.in);
        int len=Integer.parseInt(sc.nextLine());
        Value[] unsorted=new Value[len];
        Value[] sorted=new Value[len];
        String[] toStringedNumbers=new String[len];
        String[] splited=sc.nextLine().split(" ");
        for(int i=0;i<len;i++){
            String read=splited[i];
            int readI=Integer.parseInt(read);
            Value value=new Value(readI,i);
            unsorted[i]=value;
            sorted[readI-1]=value;
            toStringedNumbers[readI-1]=read;
        }
        sorted[unsorted[len-1].value-1]=used;

        int[] result=new int[len];

        len>>=1;
        for(int i=0,filled=0;filled<len;filled++,i++){
            i=findMin(sorted,i);
            Value value=sorted[i];
            int next=findNext(unsorted,value.offset);
            result[offset++]=value.value;
            result[offset++]=unsorted[next].value;

            remove(sorted,unsorted,value);
            remove(sorted,unsorted,unsorted[next]);
        }
        StringBuilder builder=new StringBuilder();
        for(int c:result){
            builder.append(toStringedNumbers[c-1]).append(" ");
        }
        System.out.println(builder.toString().replaceFirst(" $",""));
    }
    private static int findMin(Value[] sortedArr,int start){
        for(int i=start;i<sortedArr.length;i++){
            if(sortedArr[i]!=used) return i;
        }
        throw new RuntimeException();
    }
    private static int findNext(Value[] unsorted,int start){
        for(int i=start+1;i<unsorted.length;i++){
            if(unsorted[i]!=used) return i;
        }
        throw new RuntimeException();
    }
    private static void remove(Value[] sorted,Value[] unsorted,Value v){
        sorted[v.value-1]=used;
        unsorted[v.offset]=used;
    }

    private record Value(int value,int offset){}
}