var t,t1:array [1..1000] of word;
    n,m,i,j,k,s:word;
    f,g:text;
begin
assign(f,'economie.in');
reset(f);
assign(g,'economie.out');
rewrite(g);
k:=0;
read(f,n);
for i:=1 to n do
read(f,t[i]);
for i:=2 to n do begin
j:=i-1;
s:=t[i];
while (j>0) and (s<t[j]) do begin
      t[j+1]:=t[j];
      dec(j);
end;
t[j+1]:=s;
end;

j:=1;
t1[j]:=t[1];
for i:=2 to n do begin
m:=t[i]-t1[1];
while m>t1[j] do begin
m:=m-t1[1];
end;
if m<t1[1] then begin
                if t1[j]<>t[i] then begin
                inc(j);
                t1[j]:=t[i];
                end;
                end;
end;
writeln(g,j);
for i:=1 to j do
writeln(g,t1[i]);
close(f);
close(g);
end.