program p1516;

var s1,s2,s:string;

ans:double;

i,l:longint;

Begin

readln(s1);

readln(s2);

l:=length(s1);

for i:=1 to l do s:=s+'0';

for i:=1 to l do

if s[i]s1[i] then

begin

ans:=ans+1 shl (l-i);

s:='1';

end;

s:='';

for i:=1 to l do s:=s+'0';

for i:=1 to l do

if s[i]s2[i] then

begin

ans:=ans-1 shl (l-i);

s:='1';

end;

writeln(abs(ans):0:0);

End.

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