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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	}

} import java.util.Scanner; Scanner java.util 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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	}

} 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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[] x = new int[5]; x new int[5] 5 int ans = 0; ans 0 for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		} int i = 0; int i = 0; i 0 i < 5 i 5 i++ i++ i {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		} {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		} x[i] = sc.nextInt() x[i] x i sc.nextInt() sc.nextInt sc if(x[i] != i + 1) ans = i + 1; x[i] != i + 1 x[i] x i i + 1 i 1 ans = i + 1 ans i + 1 i 1 System.out.println(ans) System.out.println System.out System System.out ans String[] args args 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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	}

} 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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	}

} Main
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[] x = new int[5];
		int ans = 0;
		for(int i = 0; i < 5; i++) {
			x[i] = sc.nextInt();
			if(x[i] != i + 1) ans = i + 1;
		}
		System.out.println(ans);
		
		
		
	}

}
