import java.io.*;
import java.util.*;

/*Problem Id:1323  User Id:haroun 
Memory:4440K  Time:312MS
Language:Java  Result:Wrong Answer*/

public class Main1{
	public static void main(String args[]){
		List l = new LinkedList();
		Scanner s = new Scanner(System.in);
		int a1 = 0,a2=0 ;
		int lis = 0 ;
		Integer b ;
		boolean j=true;
		List l2 = new ArrayList();
		String st ;
		int in = 1;
		Main1 m = new Main1();
		while(j)
		{
		a1 = s.nextInt();
		a2 = s.nextInt();
		if(a1==a2 && a1==0) break;
		for(int i =0;i<a2;i++){
			lis = s.nextInt();
			b = Integer.valueOf(lis);
			l.add(b);
		}
		System.out.println("");
		int x = m.judgeL(l,a1*a2);
	    st = "case"+in+":"+x;
	    in = in+1;
	    l2.add(st);
    	}
    	Iterator il = l2.iterator();
    	while(il.hasNext()){ 
   		System.out.println((String)il.next());
   			}
	}
	/*先排序,从最小的开始处理,往后进行展望,看以后的累积的数是否都能大于前数列中的数,如果是,
	 则返回0,否则进行计算*/
	public int judgeL(List l,int range){
		Collections.sort(l);
		Iterator it = l.iterator();
		int num = 0;
		Integer te1,te2;
		int temp1 = -1,temp2 = -1,temp3;
		while(it.hasNext()){
		  temp2 = temp1; 	
		  num=  num+1;
		  te1 = (Integer)it.next();
		  temp1 = te1.intValue();
		  if(temp2!=-1 && temp2 != temp1){ //处理
		  	temp3 = temp1 - temp2 - 1;
		  	if(temp3 >0) num = num - temp3;
		  	if(num < 0) num = 0;
		  }
		  	
		}
		num = num +1;  //要算最后一个数;
		temp3 = range - temp1;
		num = num - temp3;
		if(num<0) num = 0;
		return num;
	}
}