import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int a[] = new int[2];
    a[0] = sc.nextInt();
    a[1] = sc.nextInt();
    for(int i = 1;i<=3;i++){
      int count = 0;
      for(int j = 0;j<2;j++){
        if(i != a[j]){
          count++;
        }
      }
      if(count == 2){
        System.out.println(i);
      }
    }

  }
}

/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