If condition in CSHTML file

                                <div class="DDLabel">
                                Month:@Html.DropDownList("Month"new  SelectList(new List<object>
                                        {
                                        new { value = 1 , text = "Jan"},
                                        new { value = 2 , text = "Feb"},
                                        new { value = 3 , text = "Mar"},
                                        new { value = 4 , text = "Apr"},
                                        new { value = 5 , text = "May"},
                                        new { value = 6 , text = "Jun"},
                                        new { value = 7 , text = "Jul"},
                                        new { value = 8 , text = "Aug"},
                                        new { value = 9 , text =  "Sep"},
                                        new { value = 10 , text = "Oct"},
                                        new { value = 11, text = "Nov"},
                                        new { value = 12 , text = "Dec"},
                                        }, "value", "text", 1), new { @onchange = "e_date_changed();", @style = "width:66px" })
                                </div>
                                <div class="DDLabel">
                                    Day:@Html.DropDownList("Day", new SelectList(new List<object>
                                        {
                                        new { value =1, text = "1"},
                                        new { value =2, text = "2"},
                                        new { value =3 ,text ="3"},
                                        new { value =4, text = "4"},
                                        new { value =5, text = "5"},
                                        new { value =6, text = "6"},
                                        new { value =7, text = "7"},
                                        new { value =8, text = "8"},
                                        new { value =9, text = "9"},
                                        new { value =10, text = "10"},
                                        new { value =11, text = "11"},
                                        new { value =12, text = "12"},
                                        new { value =13, text = "13"},
                                        new { value =14, text = "14"},
                                        new { value =15, text = "15"},
                                        new { value =16, text = "16"},
                                        new { value =17, text = "17"},
                                        new { value =18, text = "18"},
                                        new { value =19, text = "19"},
                                        new { value =20, text = "20"},
                                        new { value =21, text = "21"},
                                        new { value =22, text = "22"},
                                        new { value =23, text = "23"},
                                        new { value =24, text = "24"},
                                        new { value =25, text = "25"},
                                        new { value =26, text = "26"},
                                        new { value =27, text = "27"},
                                        new { value =28, text = "28"},
                                        new { value =29, text = "29"},
                                        new { value =30, text = "30"},
                                        new { value =31, text = "31"},
                                        }, "value", "text", 1), new { @onchange = "e_date_changed();", @style = "width:66px" })
                                </div>

I want a if condition. By which user if user select April month then in next DropDownList must show only 30 day and if October then it should b 31 days. How can i do this and where should be this code placed?