package Easy;

import java.util.Scanner;

public class Three2 {
    public static void main(String[] args) {
        Three2 t = new Three2();
        Scanner in = new Scanner(System.in);
        int T = in.nextInt();
        int maxMem = in.nextInt();
        int handleNum = 1;
        Mem head = t.getMemInstance();
        while
 
(in.hasNext()){
            String operation = in.next();
            if(operation.equals("def")){
                //整理記憶體不做任何輸出
                Mem p = head;
                while(p.next!=null){
                    if(p.next.isDel){
                        p.next=p.next.next;
                    }else
 
{
                        p=p.next;
                    }
                }
            }else if(operation.equals("new")){
                //申請記憶體，成功返回控制代碼值，失敗返回NULL
                int size = in.nextInt();
                Mem node = t.getMemInstance();
                node.size = size;
                Mem p = head;
                Mem begin = head;
                Mem end = head;
                int
 
 totalUsed=0;
                int innerCan = 0;
                while(p!=null){
                    totalUsed += p.size;
                    if(p.isDel){
                        end = p;
                        innerCan += p.size;
                    }else{
                        begin = p;
                        innerCan = 0;
                    }
                    if(innerCan>=size){
                        end = end.next;
                        break;
                    }
                    if(p.next!=null){
                        p=p.next;
                    }else{
                        break;
                    }
                }
                if(innerCan>size){
                    Mem newNode1 = t.getMemInstance();
                    newNode1.size = size;
                    newNode1.handleNo = handleNum;
                    System.out.println(handleNum);
                    handleNum++;
                    Mem newNode2 = t.getMemInstance();
                    newNode2.size = innerCan-size;
                    newNode2.handleNo = -1;
                    newNode2.isDel = true;
                    newNode1.next = newNode2;
                    newNode2.next = end;
                    begin.next = newNode1;
                }else if(innerCan==size){
                    Mem newNode = t.getMemInstance();
                    newNode.size = size;
                    newNode.handleNo = handleNum;
                    System.out.println(handleNum);
                    newNode.next=begin.next;
                    begin.next=newNode;
                    handleNum++;
                }else if(maxMem-totalUsed>=size){
                    Mem newNode = t.getMemInstance();
                    newNode.size = size;
                    newNode.handleNo = handleNum;
                    System.out.println(handleNum);
                    handleNum++;
                    p.next=newNode;
                }else{
                    System.out.println("NULL");
                }
            }else if(operation.equals("del")){
                //釋放控制代碼指向的記憶體，失敗返回ILLEGAL_OPERATION，成功無輸出
                int index = in.nextInt();
                Mem p = head;
                boolean canDel = false;
                if(index<handleNum){
                    while(p!=null){
                        if(p.handleNo==index){
                            if(!p.isDel){
                                p.isDel=true;
                                canDel = true;
                            }
                            break;
                        }
                        p=p.next;
                    }
                }
                if(!canDel){
                    System.out.println("ILLEGAL_OPERATION");
                }
            }
        }
    }

    private Mem getMemInstance(){
        return new Mem();
    }

    class Mem{
        public int size=0;
        public int handleNo=-1;
        public Mem next = null;
        public boolean isDel = false;
    }
}