var A:array[1..50] of integer;
n,i,X : integer;
begin
X:=0;
write('do dai cua day so la:');readln(n);
while (n<0) or (n>=50) do begin
Writeln(Hay nhap lai n=');readln(n);
for i:=1 to n do begin
readln(A[i]);
X:=X+A[i];
end;
Writeln('Tong cac phan tu cua day so la:',X);
Writeln('Trung binh cong cac phan tu cua day so la:', X/n);
readln
end.
(Mik chưa KT lỗi đâu nha)