program vid;

//{$APPTYPE CONSOLE}

//uses
//  SysUtils;

var t,a,b,c:array[1..10000] of integer;
n,m,k,i,j:integer;
s:char;
f1,f2:text;
begin
assign(f1,'long.txt');
reset(f1);
n:=0;
while not(eoln(f1)) do begin
read(f1,s);
if s='0' then begin n:=n+1;t[n]:=0;end;

if s='1' then begin n:=n+1;t[n]:=1;end;
if s='2' then begin n:=n+1;t[n]:=2;end;
if s='3' then begin n:=n+1;t[n]:=3;end;
if s='4' then begin n:=n+1;t[n]:=4;end;
if s='5' then begin n:=n+1;t[n]:=5;end;
if s='6' then begin n:=n+1;t[n]:=6;end;
if s='7' then begin n:=n+1;t[n]:=7;end;
if s='8' then begin n:=n+1;t[n]:=8;end;
if s='9' then begin n:=n+1;t[n]:=9;end;
//writeln(s,' ',n, ' ',t[n]);
//readln;
//if c in ['0'..'9'] then begin n:=n+1; t[n]:=ord(c)-48; end;
end;
for i:=n downto 1 do a[n-i+1]:=t[i];
readln(f1,s);
m:=0;
while not(eoln(f1)) do begin
read(f1,s);
if s='0' then begin m:=m+1;t[m]:=0;end;
if s='1' then begin m:=m+1;t[m]:=1;end;
if s='2' then begin m:=m+1;t[m]:=2;end;
if s='3' then begin m:=m+1;t[m]:=3;end;
if s='4' then begin m:=m+1;t[m]:=4;end;
if s='5' then begin m:=m+1;t[m]:=5;end;
if s='6' then begin m:=m+1;t[m]:=6;end;
if s='7' then begin m:=m+1;t[m]:=7;end;
if s='8' then begin m:=m+1;t[m]:=8;end;
if s='9' then begin m:=m+1;t[m]:=9;end;
//if c in ['0'..'9'] then begin n:=n+1; t[n]:=ord(c)-48; end;
end;
for i:=m downto 1 do b[m-i+1]:=t[i];

close(f1);

k:=n;
for i:=1 to k do
if a[i]>=b[i] then c[i]:=a[i]-b[i] else begin c[i]:=a[i]+10-b[i];a[i+1]:=a[i+1]-1;end;

i:=k;
while (c[i]=0) and (i>1)do i:=i-1;
k:=i;
assign(f2,'rez.txt');
rewrite(f2);
for i:=k downto 1 do write(f2,c[i]);
writeln(f2);
close(f2);
end.