program stroki;
var
s,p : string;
d,i : longint;
BEGIN
readln(s);
d:=length(s);
p:=s[1];
for i:=2 to d do
if pos(s[i],p)=0
then p:=s[i]+p;
write(p);
END.
program stroki;
var
s,p : string;
d,i : longint;
BEGIN
readln(s);
d:=length(s);
p:=s[1];
for i:=2 to d do
if pos(s[i],p)=0
then p:=s[i]+p;
write(p);
END.