import java.io.*;
import java.util.Scanner;


public class Main_yukicoder791 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		char[] n = sc.next().toCharArray();

		if (n[0] != '1' && n.length == 1) {
			pr.println(-1);
			return;
		}
		
		for (int i = 1, size = n.length; i < size; i++) {
			if (n[i] != '3') {
				pr.println(-1);
				return;
			}
		}
		
		pr.println(n.length - 1);
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);
			
		solve();
			
		pr.close();
		sc.close();
	}

	static class Printer extends PrintWriter {
		Printer(OutputStream out) {
			super(out);
		}
	}
}