Системы счисления

const alf = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
var
    x,y,z:string;
    osnovanie:byte;
 
 
procedure plus(a,b:string; p :byte; var c:string);
var i,ost,x:integer;
begin
  c:='';
  while length(a) < length (b) do
    a := '0' + a;
  while length(b) < length(a) do
    b := '0' + b;
  ost := 0;
  for i := length(a) downto 1 do
    begin
      x := (pos(a[i],alf)-1 + pos(b[i],alf)-1+ost) mod p;
      ost := (pos(a[i],alf)-1 + pos(b[i],alf)-1+ost) div p;
      c := alf[x+1] + c;    
    end;
  if ost <> 0 then
    c := alf[ost+1] + c;
end;
 
procedure umnozh(a,b:string; p :byte; var tmp1:string);
var i,j,ost,x,k:integer;
    c:string;
begin
tmp1:='';
while length(a) < length (b) do
    a := '0' + a;
  while length(b) < length(a) do
    b := '0' + b;
   for i := length(a) downto 1 do
    begin
     c:='';
     ost:=0;
     for j := length(b) downto 1 do
      begin 
       x := ((pos(a[i],alf)-1) * (pos(b[j],alf)-1)+ost) mod p;
       ost := ((pos(a[i],alf)-1) * (pos(b[j],alf)-1)+ost) div p;
       c := alf[x+1] + c ;    
      end;
     if ost <> 0 then
    c := alf[ost+1] + c ;
    for k:=i+1 to length(a) do
      c:=c+'0';
  plus(tmp1,c,p,tmp1);
end;
end;
 
 
 procedure minus(a,b:string; p :byte; var c:string);
var i,ost,x:integer;
begin
  c:='';
  while length(b) < length(a) do
    b := '0' + b;
  ost := 0;
  for i := length(b) downto 1 do
    begin
      x := (pos(a[i],alf)-1 - (pos(b[i],alf)-1)+p-ost) mod p;
      if pos(b[i],alf)>pos(a[i],alf) then 
        ost:=1
       else
        ost:=0;
    
      c := alf[x+1] + c;    
    end;
end;
 
 
begin
 
  plus('675','546',8,z);
  writeln(z);
  umnozh('675','546',8,z);
  writeln(z);
  minus('675','546',8,z);
  writeln(z); 
 
end.