Can anybody help me with test 2? What is it?
I use merge sort.

I use qsort and have the same situation.

You need to use stable sort.
Bubble sort is stable nad qsort isn't.

I used std::stable_sort() from C++ tempate library.
Here also can be used linear radix stable sort or counting sort.

i use counting sort, and got AC in 0.187s.
=======core=======
  fillchar(c,sizeof(c),0);
  for i:=1 to n do inc(c[a[i].m]);
  for i:=99 downto 0 do inc(c[i],c[i+1]);
  for i:=n downto 1 do
    begin
      b[c[a[i].m]]:=a[i];
      dec(c[a[i].m])
    end;
==================

I used merge sort and I've got AC.

Use this test:
6
1 1
2 1
3 2
4 2
5 3
6 3

Right Answer is:
5 3
6 3
3 2
4 2
1 1
2 1