import java.util.*;
public class Main{
	public static void main(String[] args){
    	Scanner sc=new Scanner(System.in);
     	int[] x=new int[4];
      	for(int i=0;i<2;i++){
        	int m=sc.nextInt();
          		x[m]++;
        }
      	for(int i=1;i<=3;i++){
        	if(x[i]==0){
            	System.out.print(i);
              	break;
            }
        }
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz