import java.util.*;
import java.lang.*;
import java.io.*;
 
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println(countInitialZeros("0005606"));
		System.out.println(countInitialZeros("005606"));
		System.out.println(countInitialZeros("05606"));
		System.out.println(countInitialZeros("5606"));
		System.out.println(countInitialZeros("0000"));
	}
	public static int countInitialZeros(String haystack) {
	    return haystack.replaceFirst("^(0*)[1-9]\\d*$", "$1").length();
	}
}

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