Реализовать удаление листьев с отрицательными значениями

Program siaod_lab2;
uses crt;
const
     TAB = chr(9);
type
Tree = ^Node;
Node = record
     data: integer;
     left: Tree;
     right: Tree;
end;
Var Root,T,p: Tree;
f: text;
w, count: integer;
wght: real;
level: integer;
c: char;
procedure ReadTree(var F: Text; var T: tree);
 
  var
    level: Integer;
    currLine: String;
    currNumber: String;
    dataStr: String;
    currPos: Integer;
    code: Integer;
 
    function GetWord: String;
 
    var
      result: String;
 
    begin
      while (currPos <= Length(currLine)) and ((currLine[currPos] = ' ')
            or (currLine[currPos] = TAB)) do
        currPos := currPos + 1;
      result := '';
      while (currPos <= Length(currLine)) and (currLine[currPos] <> ' ')
            and (currLine[currPos] <> TAB) do begin
        result := result + currLine[currPos];
        currPos := currPos + 1;
      end;
      GetWord := result;
    end; {GetWord}
 
    procedure RecurseRT(var T: Tree; level: Integer);
    
 
    begin
      T := New(Tree);
      T^.Left := nil;
      T^.Right := nil;
      dataStr := GetWord; 
      Val(dataStr, T^.Data, Code);
      Readln(F, currLine);
      currPos := 1;
      currNumber := GetWord;
      while Length(currNumber) > level do begin 
        if currNumber[Length(currNumber)] = '0' then
          RecurseRT(T^.Left, level + 1)
        else
          RecurseRT(T^.Right, level + 1);
      end;
    end; {RecurseRT}
 
  begin {ReadTree}
    if EOF(F) then 
      T := nil
    else begin
      Readln(F, currLine);
      currPos := 1;
      currNumber := GetWord;
      RecurseRT(T, 1);
    end;
  end; {ReadTree}
   procedure PrintTree(Header: String; var T: Tree);
 
    procedure RecursePT(T: Tree; number: String);
  
 
    var
      i: Integer;
 
    begin {RecursePT}
      if T = nil then
        Exit;
   
      for i := 1 to Length(number) do 
        Write(' ');
      Write(number + '  ');
      Writeln(T^.Data);
     
      RecursePT(T^.Left,  number + '0');
      RecursePT(T^.Right, number + '1');
    end; {RecursePT}
 
  begin {PrintTree}
    Writeln;
    Writeln(Header);
    RecursePT(T, '0');
  end; {PrintTree}
 
function Del_leaves(var p:tree):boolean;
var
  Lt,Rg:boolean;
begin
    Del_leaves:=false;
   if p=nil  then exit;
    Del_leaves:=true;
    Rg :=del_leaves(p^.right);
    Lt :=del_leaves(p^.left);
   if not(Lt or Rg) then
    dispose(p);
    p:=nil;
 end;
 
Begin
writeln('1 del');
readln(c);
if c ='1' then
Del_leaves(p);
readln;
clrscr;
assign(f,'c:\Tr1.txt');
reset(f);
ReadTree(f,T);
Root:= T;
w:= 0;
wght:= 0;
count:= 0;
level:= 0;
PrintTree('Tree',T);
level:= 0;
End.