#include <iostream>

 #include <cstdio>

 #include <algorithm>

 #include <cstring>

 #include <cmath>

 #include <vector>

 #include <set>

 #define inf 1000000007

 #define maxn 100002

 using namespace std;

 int n;

 int seq[maxn];

 struct peo

 {

     int h,x;

     friend bool operator <(peo a, peo b)

     {

         return a.h<b.h;

     }

 }a[maxn];

 struct bit

 {

     int b[maxn];

     int num;

     void add(int x,int z)

     {

         for (int i=x;i<=num;i+=(i&-i)) b[i]+=z;

     }

     int ask(int x)

     {

         int tmp=;

         for (int i=x;i;i-=(i&-i)) tmp+=b[i];

         return tmp;

     }

     void init(int n)

     {

         num=n;

         memset(b,,sizeof(b));

     }

 }s;

 int main()

 {

     int Case;

     scanf("%d",&Case);

     for (int o=;o<=Case;o++)

     {

         int flag=;

         scanf("%d",&n);

         for (int i=;i<=n;i++)

             scanf("%d%d",&a[i].h,&a[i].x);

         sort(a+,a+n+);

         s.init(n);

         for (int i=;i<=n;i++) s.add(i,);

         for (int i=;i<=n;i++)

         {

             int tmp=inf, k=a[i].x;

             if (<=k+ && k+<=n-i+) tmp=min(tmp,k+);

             if (<=n-i-k+ && n-i-k+<=n-i+) tmp=min(tmp,n-i-k+);

             if (tmp==inf)

             {

                 flag=;

                 break;

             }

             int l=,r=n, now;

             while (l<=r)

             {

                 int mid=(l+r)>>;

                 if (s.ask(mid)>=tmp)

                 {

                     now=mid;

                     r=mid-;

                 }

                 else

                     l=mid+;

             }

             seq[now]=a[i].h;

             s.add(now,-);

         }

         printf("Case #%d: ",o);

         if (!flag) printf("impossible\n");

         else

             for (int i=;i<=n;i++)

                 if (i<n) printf("%d ",seq[i]);

                 else printf("%d\n",seq[i]);

     }

     return ;

 }