how to get dropped element ID , dragDrop Angular

Question

i use this function on drop from task planned into task progress

onDrop1(event:CdkDragDrop<string[]>,id:any){
      console.log('ondrop progress')
      this.updateProgress()
      if(event.previousContainer===event.container){
        
      moveItemInArray(
        event.container.data,
        event.previousIndex,
        event.currentIndex
    
      );
      }else{
        transferArrayItem(
          event.previousContainer.data,
          event.container.data,
          event.previousIndex,
          event.currentIndex,

        );
      }
       }

and this is the HTML code

<h1>planned</h1>
<div  cdkDropList id="tasks_planned" [cdkDropListConnectedTo]="['tasks_progress']" (cdkDropListDropped)="onDrop($event)" 
  [cdkDropListData]="tasks_planned">
  <div cdkDrag class="drag-item"  *ngFor="let tache of tasks_planned">
    {{tache.description}}
  </div>
</div>
<h1>progress</h1>
<div cdkDropList id="tasks_progress" [cdkDropListConnectedTo]="['tasks_completed']" (cdkDropListDropped)="onDrop1($event,5)" 
  [cdkDropListData]="tasks_progress">
  <div cdkDrag class="drag-item" *ngFor="let tachep of tasks_progress" cdkDrag [cdkDragData]="tachep.id">
    {{tachep.description}}
  </div>
</div>

so i want to get the id of the element , to be draged