Var
  a: array[1..100] of Integer;
  n, i, dem, sum: Integer;
  avg: Real;
Begin
  Write('Nhap so phan tu cua day so: ');
  Readln(n);
  dem := 0;
  sum := 0;
  For i := 1 to n do
  Begin
    Write('Nhap phan tu thu ', i, ': ');
    Readln(a[i]);
    If a[i] > 0 then
    Begin
      dem := dem + 1;
      sum := sum + a[i];
    End;
  End;
  If dem = 0 then
    Writeln('Khong co so duong nao.')
  Else
  Begin
    avg := sum / dem;
    Writeln('Trung binh cong cua cac so duong la: ', avg:0:2);
  End;