求1*3*5*7...*N（N小于15）

program djedk;
var
　　n, s, i:integer;
begin
　　read(n);
　　s := 1;
　　for i := 3 to n do
　　　　if i mod 2 = 1 then
　　　　　　s := s*i;
　　writeln(s);
end.

=================== OR =====================

program djedk;
var
  n, s, i, j : integer;
begin
  write('Please input a number: ');
  readln(n);
  if n mod 2 = 0 then n := n -1;
  s := 1;
  for i := 1 to n div 2 do
      s := s * (i+i+1);
  writeln('product: ', s);
  readln;
end.

====================== OR ====================

program djedk;
var
  n, s : integer;
begin
  write('Please input a number: ');
  readln(n);
  if n mod 2 = 0 then n := n -1;
  s := 1;
  for n := n div 2 downto 1 do
      s := s * (n+n+1);
  writeln('product: ', s);
  readln;
end.