function sem(){
    let sem = document.getElementById("sender_address").value;
 
    window.location.replace("https://localhost/af/index.php?page=student_filter&sem="+sem);
      
    }
  
function sem1(){
     
    let sem1 = document.getElementById("sender_address1").value;

    window.location.replace("https://localhost/af/index.php?page=student_filter&sem="+$sem+"&&sem1="+sem1);
      
}