#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
priority_queue<int,vector<int>,greater<int> >Heap;
#define lson rt<<1,l,m
#define rson rt<<1|1,m+1,r
int v[200005],first[200005],nex[200005],e;
void AddEdge(int U,int V){v[++e]=V;nex[e]=first[U];first[U]=e;
}
int a[200005],cnt,ma[200005],pai[200005];
int minv[2][100005<<4],n,pos[200005];
void update(int o,int p,int v,int rt,int l,int r)
{if(l==r){minv[o][rt]+=v;return;}int m=(l+r>>1);if(p<=m) update(o,p,v,lson);else update(o,p,v,rson);minv[o][rt]=min(minv[o][rt<<1],minv[o][rt<<1|1]);
}
int query(int o,int ql,int qr,int rt,int l,int r)
{if(ql<=l&&r<=qr) return minv[o][rt];int m=(l+r>>1);int res=2147483647;if(ql<=m) res=min(res,query(o,ql,qr,lson));if(m<qr) res=min(res,query(o,ql,qr,rson));return res;
}
void work(int l,int r,int f){if(l>=r){return;}int L=pos[query(l&1,ma[l],(l%2 == r%2) ? ma[r] : ma[r-1],1,1,n/2)];int R=pos[query((L+1)&1,ma[L+1],((L+1)%2 == r%2) ? ma[r] : ma[r-1],1,1,n/2)];pai[a[L]]=a[R];AddEdge(a[f],a[L]);work(l,L-1,f);work(L+1,R-1,L);work(R+1,r,f);
}
int main(){
//  freopen("c.in","r",stdin);scanf("%d",&n);for(int i=1;i<=n;++i){scanf("%d",&a[i]);pos[a[i]]=i;update(i&1,i/2+(i&1),a[i],1,1,n/2);ma[i]=i/2+(i&1);}if(n==2){printf("%d %d\n",a[1],a[2]);return 0;}work(1,n,0);for(int i=first[0];i;i=nex[i]){Heap.push(v[i]);}while(!Heap.empty()){int U=Heap.top(); Heap.pop();cnt+=2;printf("%d %d%c",U,pai[U],cnt==n ? '\n' : ' ');for(int i=first[U];i;i=nex[i]){Heap.push(v[i]);}}return 0;
}