Can anyone help me below mentioned code showing wrong result for last 3 test case.

import java.io.; import java.math.; import java.security.; import java.text.; import java.util.; import java.util.concurrent.; import java.util.function.; import java.util.regex.; import java.util.stream.*; import static java.util.stream.Collectors.joining; import static java.util.stream.Collectors.toList;

// class Result {

public static HashMap<HashMap<Integer,Integer>,Integer> hm = new HashMap<>();
public static int grundy(int x,int y){
    HashMap<Integer,Integer> p = new HashMap<>();
    p.put(x,y);
    if(hm.containsKey(p)) return hm.get(p); 
    HashSet<Integer> set = new HashSet<>();
    if(x>=1 && y>=1 && x<=15 && y<=15){
        set.add(grundy(x-2, y+1));
        set.add(grundy(x-2, y-1));
        set.add(grundy(x+1, y-2));
        set.add(grundy(x-1, y-2));
    }
    int mex;
    for(int i = 0; ; i++)
    {
        if(set.contains(i)){
            continue;
        }
        mex = i;
        break;
    }
    // g = !g;
    hm.put(p, mex);
    return mex;

 }

public static String chessboardGame(int[][] coins) {
// Write your code here
    int xorsum = 0;
    for(int i = 0; i < coins.length; i++){
        int x = coins[i][0];
        int y = coins[i][1];

        // System.out.println("x="+x+"  y ="+y);

        int g = grundy(x, y);

        xorsum ^= g;
        // System.out.println(g);
    }
    // System.out.println(hm);
    return xorsum == 0?"Second":"First";

}

}

public class Solution { public static void main(String[] args) throws IOException { Scanner sc = new Scanner(System.in); int t = sc.nextInt(); while(t-->0){ int k = sc.nextInt(); int[][] arr = new int[k][2]; for(int i = 0 ; i < k; i++){ arr[i][0] = sc.nextInt(); arr[i][1] = sc.nextInt(); } String result = Result.chessboardGame(arr); System.out.println(result); } } }