import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int x1 = sc.nextInt();
		int x2 = sc.nextInt();
		int x3 = sc.nextInt();
		int x4 = sc.nextInt();
		int x5 = sc.nextInt();
		int x[] = {x1, x2, x3, x4, x5};
		for(int i=0; i < x.length; i++) {
			if(x[i] == 0) {
				System.out.println(i + 1);
			}
		}
	}

}
/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