uses crt;
var n,i,nn,tam,j,tt:longint;s,t,p:string;
a,b:array[1..100000] of longint;
begin
readln(n);  nn:=n;
str(n,s);i:=length(s);
repeat
a[i]:=n mod 10;
n:=n div 10;
dec(i);
until n=0;

for i:=1 to length(s)-1 do
for j:=i+1 to length(s) do
if a[i]>a[j] then begin
tam:=a[i];
a[i]:=a[j];
a[j]:=tam;
end;
        j:=0;
repeat
inc(j);
str(a[j],p);
t:=t+p;
until j=length(s);
val(t,tt);
if tt=nn then begin write(-1);readln;exit;end;
if n>tt then write(-1) else write(tt);
readln
end.