import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner sr = new Scanner(System.in);
    int X[] = new int[5];
    for(int i=0;i<=4;i++)
      X[i] = sr.nextInt();
    for(int j:X)
      if(X[j]==0){System.out.println(j+1);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