var
  a:array[0..14000] of integer;
  b:array[0..25000] of integer;
  n,i,j,k,max:integer;

begin
  readln(n);
  fillchar(a,sizeof(a),0);fillchar(b,sizeof(b),0);    b[0]:=1;max:=0;
  for i:=0 to n-2 do begin
    readln(a[i]);
    if a[i]=-1 then begin writeln(max);halt;end;
    inc(b[a[i]]);
    if a[i]>max then max:=a[i];
  end;
  readln(j);
  while j>=0 do begin
    inc(i);
    i:=i mod n;
    dec(b[a[i]]);a[i]:=j;
    inc(b[j]);
    if j>max then max:=j;
    k:=max;
    if b[max]=0 then for max:=k-1 downto 0 do if b[max]>0 then break;
    writeln(max);
    readln(j);
  end;
end.

for 3: 108900
and for 4: 598950

Excuse me !! This are some tests for 1206 .

---------------------------------------------

Here is a "good" test for 1126 :

Input :

5
0
1
2
3
4
5
6
7
8
9
10
10
9
8
7
6
5
4
3
2
1
10
11
12
0
0
0
0
0
1
2
10
2
-1


Output :

4
5
6
7
8
9
10
10
10
10
10
10
9
8
7
6
5
10
11
12
12
12
12
12
0
1
2
10
10

> Excuse me !! This are some tests for 1206 .
>
> ---------------------------------------------
>
> Here is a "good" test for 1126 :
>
> Input :
>
> 5
> 0
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
> 10
> 10
> 9
> 8
> 7
> 6
> 5
> 4
> 3
> 2
> 1
> 10
> 11
> 12
> 0
> 0
> 0
> 0
> 0
> 1
> 2
> 10
> 2
> -1
>
>
> Output :
>
> 4
> 5
> 6
> 7
> 8
> 9
> 10
> 10
> 10
> 10
> 10
> 10
> 9
> 8
> 7
> 6
> 5
> 10
> 11
> 12
> 12
> 12
> 12
> 12
> 0
> 1
> 2
> 10
> 10

Your problem is in the array constraints:
b:array[0..25000] of integer;
The problem states that the values are between 0 and 100000, so b
[100000] does not exist...

> Your problem is in the array constraints:
> b:array[0..25000] of integer;
> The problem states that the values are between 0 and 100000, so b
> [100000] does not exist...

Got AC with this...
var
  a:array[0..14000] of longint;
  b:array[0..100000] of longint;
  n,i,j,k,max:longint;

begin
{The rest is the same}
end.
Got AC with this...