XOR

var
  i,j : integer;
begin
  readln(i);
  readln(j);
  i:= i xor j;
  writeln('xor - ', i);
end.

var a, b: string;
dig_a, dig_b: array of integer;
 
procedure Push_front<T>(var a: array of T; x: T);
begin
  SetLength(a, length(a) + 1);
  for i: integer := length(a) - 1 downto 1 do
  begin
    a[i] := a[i - 1]
  end;
  a[0] := x;
end;
 
begin
  readln(a);
  readln(b);
  foreach i: char in a do
  begin
    Push_front(dig_a, StrToInt(a[length(a)]));
    SetLength(a, length(a) - 1);
  end;
  foreach i: char in b do
  begin
    Push_front(dig_b, StrToInt(b[length(b)]));
    SetLength(b, length(b) - 1);
  end;
  while(length(dig_a) > length(dig_b)) do
    Push_front(dig_b, 0);
  while(length(dig_b) > length(dig_a)) do
    Push_front(dig_a, 0);
  for i: integer := 0 to length(dig_a) - 1 do
    write(dig_a[i] xor dig_b[i]);
end.

function bintodec(s:string):integer;
var n,i:integer;
begin
n:=0;
for i:=length(s) downto 1 do
if s[i]='1' then inc(n,round(power(2,length(s)-i)));
result:=n;
end;
function dectobin(n:integer):string;
var s:string;
begin
s:='';
while n>0 do
 begin
  s:=inttostr(n mod 2)+s;
  n:=n div 2;
 end;
result:=s;
end;
var s1,s2:string;
begin
s1:='1111';
s2:='1000';
write(dectobin(bintodec(s1) xor bintodec(s2)))
end.

var
  s, t: String;
  i: Integer;
begin
  Write('1: '); ReadLn(s);
  Write('2: '); ReadLn(t);
  for i:=1 to Length(s)-Length(t) do t:='0'+t;
  for i:=1 to Length(t)-Length(s) do s:='0'+s;
  for i:=1 to Length(s) do s[i]:=Chr(Ord('0')+Ord(s[i]<>t[i]));
  WriteLn('R: ',s);
end.

procedure XorIt(s, t: Longint);
begin
  if s div 10+t div 10<>0 then XorIt(s div 10, t div 10);
  Write((s and 1) xor (t and 1));
end;
var s, t: Longint;
begin
  Write('1: '); ReadLn(s);
  Write('2: '); ReadLn(t);
  Write('R: '); XorIt(s,t); WriteLn;
end.

for i:=1 to Length(t)-Length(s) do s:='0'+s;
for i:=1 to Length(s) do s[i]:=Chr(Ord('0')+Ord(s[i]<>t[i]));

const ZO: array [Boolean] of Char = ('0','1');
...
  for i:=1 to Length(s) do s[i]:=ZO[s[i]<>t[i]];