uses crt;
var a,b,c:array[1..100]of integer;
i,n,dem,dem1,j,tam:integer;
begin
clrscr;
write('Nhap n='); readln(n);
for i:=1 to n do
begin
write('a[',i,']='); readln(a[i]);
end;
dem:=0;
dem1:=0;
for i:=1 to n do
begin
if a[i]>0 then
begin
inc(dem);
b[dem]:=a[i];
end;
if a[i]<0 then
begin
inc(dem1);
c[dem1]:=a[i];
end;
end;
if (n mod 2=0) and (dem=dem1) then
begin
for i:=1 to dem-1 do
for j:=i+1 to dem do
if b[i]>b[j] then
begin
tam:=b[i];
b[i]:=b[j];
b[j]:=tam;
end;
for i:=1 to dem1-1 do
for j:=i+1 to dem1 do
if c[i]<c[j] then
begin
tam:=c[i];
c[i]:=c[j];
c[j]:=tam;
end;
for i:=1 to dem do
for j:=1 to dem1 do
if i=j then write(c[j],' ',b[i],' ');
end
else writeln('Vui long nhap lai');
readln;
end.