const fi='xau.inp';
fo='xau.out';
var f1,f2:text;
st:array[1..100]of string;
i,d:integer;
st1:shortstring;
begin
assign(f1,fi); reset(f1);
assign(f2,fo); rewrite(f2);
d:=0;
while not eof(f1) do
begin
inc(d);
readln(f1,st[d]);
end;
st1:='';
for i:=1 to d do
st1:=st1+st[i];
for i:=1 to length(st1) do
if st1[i]='a' then write(f2,st1[i]:4);
close(f1);
close(f2);
end.