function doSubmit(f) {
  var e=0; var found=0;
  var no = 0;  
  for (var intLoop = 1; intLoop<11; intLoop++) {        
    var name =document.getElementById("friendname"+intLoop).value;
    var email = document.getElementById("emailid"+intLoop).value;
    if(name.length == 0 && email.length == 0){        
        no = no +1;
    }
  }  
  
  if (no == 10){
      e |=1;
  }else{ 
      var noname = 0;
      var noemail = 0;
      
      for (var intLoop = 1; intLoop<11; intLoop++) {        
        var name =document.getElementById("friendname"+intLoop).value;
        var email = document.getElementById("emailid"+intLoop).value;
        if(name.length > 0 && email.length == 0){
            noemail = noemail + 1;
        }else if (name.length == 0 && email.length > 0){
            noname = noname + 1;
        }   
      }  
      
      if (noname > 0 && noemail > 0){
          e |= 1;
      }else if (noname > 0 && noemail == 0){
          e |= 3;
      }else if (noname == 0 && noemail > 0){
          e |= 2
      }
  }       
  var result = false;
  var error_msg = null;
  switch (e) {
  case 1:
    error_msg = "Please enter Name and Email address";
    break;
  case 2:
    error_msg = "Please enter email address";
    break;
  case 3:
    error_msg = "Please enter the name of the person";
    break;  
  default:
    result = true;
    break;
  }
  if (error_msg != null)
    alert (error_msg);
  return result;
}