#include<cstdio>

 #include<algorithm>

 using namespace std;

 struct point {

     int h,k;

     bool operator <(const point & a)const

     {

        return h<a.h;

     }

 };

 point yj[];

 int res[];

 struct node{

     int l,r,x;

 };

 node tree[*];

 void build(int i,int left,int right)

 {

     tree[i].l=left;tree[i].r=right;

     if (left==right)

     {

         tree[i].x=;

         return ;

     }

     int mid=(left+right)>>;

     build(i<<,left,mid);

     build(i<<|,mid+,right);

     tree[i].x=tree[i<<].x+tree[i<<|].x;

 }

 void update(int i,int ans,int num)

 {

     if (tree[i].l==tree[i].r)

     {

         tree[i].x=;

         res[tree[i].l]=num;

         return ;

     }

     int mid=(tree[i].l+tree[i].r)>>;

     if (ans<=tree[i<<].x)  update(i<<,ans,num);

     else   update(i<<|,ans-tree[i<<].x,num);

     tree[i].x=tree[i<<].x+tree[i<<|].x;

 }

 int main()

 {

     int t,i,q=,n;

     scanf("%d",&t);

     while (t--)

     {

             scanf("%d",&n);

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

                 scanf("%d %d",&yj[i].h,&yj[i].k);

             sort(yj+,yj+n+);

             build(,,n);

             int flag=;

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

             {

                 int m=n-i;

                 int temp=m-yj[i].k;

                 if (temp<)

                 {

                     flag=;

                     break;

                 }

                 if (temp>yj[i].k) update(,yj[i].k+,yj[i].h);

                 else update(,temp+,yj[i].h);

             }

             printf("Case #%d: ",q++);

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

             else

             {

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

                 {

                     if (i!=n) printf("%d ",res[i]);

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

                 }

             }

     }

     return ;

 }