you can just bruteforce one char at a time to get the flag.

public class Exploit{

public static void main(String args[]) {
flag();
}

public static void flag() {
String flag = "";
char[] heck = "001002939948347799120432047441372907443274204020958757273".toCharArray();
String[] quack = {"\uffc8","\uffbd","\uffce","\uffbc","\uffca","\uffb7","\uffc5","\uffcb","\u0005","\uffc5","\uffd5","\uffc1","\uffff","\uffc1","\uffd8","\uffd1","\uffc4","\uffcb","\u0010","\uffd3","\uffc4","\u0001","\uffbf","\uffbf","\uffd1","\uffc0","\uffc5","\uffbb","\uffd5","\uffbe","\u0003","\uffca","\uffff","\uffda","\uffc3","\u0007","\uffc2","\u0001","\uffd4","\uffc0","\u0004","\uffbe","\uffff","\uffbe","\uffc1","\ufffd","\uffb5"};
for(int i=0;i