program suijishu;

var

n,i,j,k,temp,m:integer;

a:array[1..100] of integer;

begin

readln(n);

for i:=1 to n do

read(a[i]);

for i:=1 to n-1 do

for j:=i+1 to n do

if a[i]=a[j] then begin

for k:=j+1 to n do

a[k-1]:=a[k];

n:=n-1;

end;

m:=n;

for i:=1 to n-1 do

for j:=i+1 to n do

if a[i]>a[j] then begin

temp:=a[i];

a[i]:=a[j];

a[j]:=temp;

end;

writeln(m);

for i:=1 to m do

write(a[i],' ');

end.