var a,c,i,j,temp:integer;
arr,b:array[0..100]of integer;

begin
while not eof do begin
readln(a);
arr[0]:=0;
for i:=1 to a do read(arr[i]);
readln;
for i:=1 to a-1 do
for j:=i+1 to a do
if arr[j]<arr[i] then begin
temp:=arr[i];
arr[i]:=arr[j];
arr[j]:=temp;
end;
c:=0;
for i:=1 to a do
if arr[i]<>arr[i-1] then begin
inc(c);
b[c]:=arr[i];
end;
writeln(c);
for i:=1 to c-1 do
write(b[i],' ');
writeln(b[c]);
end;
end.