find unflipped cells in binary matrix

import java.util.*;

/*

given an N x M binary matrix , there are Q queries in each query which is i,j a position in the matrix
you need to select the row i and column j and flip the values ,
v1 - thing is the i,j position changes only one time
v2 - thing is the i,j position changes twice
find the unchanged cells after all the q queries



note - here the q queries use 0 based indexing

 */

 /*

//inputs for array , given you the N x M and then the binary matrix and then q queries
3 3
0 0 1
0 1 0
1 0 0
2
2 0
1 1

expected output -
The result is 5


 */


@SuppressWarnings("unused")
public class A20243012_googleOA {

    static Scanner sc = new Scanner(System.in);

    private static int[] getArray() {
        String[] sArr = sc.nextLine().split(" ");
        int[] arr = Arrays.stream(sArr).mapToInt(Integer::parseInt).toArray();
        return arr;
    }

    private static char[] getCharArray() {
        String[] sArr = sc.nextLine().split(" ");
        char[] cArr = new char[sArr.length];
        for (int i = 0; i < sArr.length; i++) {
            cArr[i] = sArr[i].charAt(0); // Take the first character of each string
        }
        return cArr;
    }

    private static int getMax(int[] arr) {
        int currMax = Integer.MIN_VALUE;
        for (int curr : arr) {
            currMax = Math.max(currMax, curr);
        }
        return currMax;
    }

    public static void main(String args[]) {
        // prepare the inputs

        int[] arr = getArray();
        int N = arr[0];
        int M = arr[1];
        int[][] binMat = new int[N][M];
        for(int i = 0;i<N;i++){
            binMat[i] = getArray();
        }
        int q = getArray()[0];
        // System.out.println("q is"+q);
        HashMap<Integer,Integer> rowMap = new HashMap<>();
        HashMap<Integer,Integer> colMap = new HashMap<>();
        HashMap<Pair,Integer> pairMap = new HashMap<>();
        for(int i=0;i<q;i++){
            int[] query = getArray();
            Pair pair = new Pair(query[0],query[1]);
            rowMap.put(pair.row,rowMap.getOrDefault(pair.row,0)+1);
            colMap.put(pair.col,colMap.getOrDefault(pair.col,0)+1);
            pairMap.put(pair,pairMap.getOrDefault(pair,0)+1);
        }
        // System.out.println("hii");

        int changedCount=0;
        for(int i=0;i<N;i++){
            for(int j=0;j<M;j++){
                Pair pair = new Pair(i,j);
                int rowFreq = rowMap.getOrDefault(pair.row,0);
                int colFreq = colMap.getOrDefault(pair.col,0);
                int pairFreq = pairMap.getOrDefault(pair,0);

                int currFlipped =(rowFreq)+(colFreq)-pairFreq;//for v2 just remove the pairFreq
                if(currFlipped%2!=0){
                    // System.out.println(" pair.row "+pair.row+" pair.col "+pair.col+" is changed ");
                    changedCount+=1;
                }
            }
        }
        int res = N*M-changedCount;

        System.out.println("The result is " + res);

    }
}

class Pair{
    int row;
    int col;
    public Pair(int i,int j){
        this.row = i;
        this.col = j;

    }
}