program schimbare_vector;
type vector = array[1..100] of integer;
var v:vector;
i,n,aux:integer;
begin
repeat
write('Introdu numarul de elemente ale vectorului:');readln(n);
until (n mod 2=0);
{citirea vectorului}
for i:=1 to n do
begin
write('v[',i.']=');readln(v[i]); end;
{schimbare}
i:=1;
while (i<n) do
begin
aux:=v[i];
v[i]:=v[i+1];
v[i+1]:=aux;
i:=i+2; end;
{afisaj}
for i:=1 to n do
write(v[i],' ');
readln;
end.