var
a,s:string;
begin
a:='0123456789';
readln(s);
if copy(a,1,length(s))=s then writeln('yes') else writeln('no');
readln;
end.
var
a,s:string;
begin
a:='0123456789';
readln(s);
if copy(a,1,length(s))=s then writeln('yes') else writeln('no');
readln;
end.