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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4.  
  5. class Ideone
  6. {
  7. public static void main (String[] args) throws java.lang.Exception
  8. {
  9. System.out.println(countInitialZeros("0005606"));
  10. System.out.println(countInitialZeros("005606"));
  11. System.out.println(countInitialZeros("05606"));
  12. System.out.println(countInitialZeros("5606"));
  13. System.out.println(countInitialZeros("0000"));
  14. System.out.println(countInitialZeros("abc"));
  15. }
  16. public static int countInitialZeros(String haystack) {
  17. return haystack.matches("\\d+") ? haystack.replaceFirst("^(0*)[1-9]\\d*$", "$1").length() : -1;
  18. }
  19. }
Success #stdin #stdout 0.04s 4386816KB
stdin
Standard input is empty
stdout
3
2
1
0
4
-1