my program here:

program tree_bianli;
const max=30000;
type arr0=record
          data:longint;
          lchild,rchild:longint;
          end;
var t:array[0..max] of arr0;
    i,n,num:longint;
    w:array[0..max] of longint;
    f:array[0..60000] of longint;
procedure readdata;
var i,j,y:longint;
begin
readln(n);
for i:=1 to n do
 begin
  read(t[i].data);
  f[t[i].data]:=i;
 end;
end;
procedure find(f,r,m:longint);
var i:longint;
begin
i:=f;
while t[i].data<t[m].data do inc(i);
dec(i);
if i>=f then t[m].lchild:=t[i].data;
if r-1>=i then t[m].rchild:=t[r].data;
if i>f then find(f,i-1,i);
if r-1>i then find(i+1,r-1,r);
end;
procedure print(p:longint);
begin
if t[p].rchild<>0 then print(f[t[p].rchild]);
if t[p].lchild<>0 then print(f[t[p].lchild]);
inc(num);w[num]:=t[p].data;
end;
BEGIN
readdata;
find(1,n-1,n);
print(n);
for i:=1 to num-1 do write(w[i],' ');writeln(w[num]);
END.

I think you go out of the array somewhere. Check it with N=30000.