Coverage of all Zeros in a Binary Matrix

class Solution {
    public int FindCoverage(int[][] matrix) {
        int cnt = 0;
        int n = matrix.length;
        int m = matrix[0].length;

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (matrix[i][j] == 0) {
                    if (j > 0 && matrix[i][j - 1] == 1)
                        cnt++;

                    if (i < n - 1 && matrix[i + 1][j] == 1)
                        cnt++;

                    if (j < m - 1 && matrix[i][j + 1] == 1)
                        cnt++;

                    if (i > 0 && matrix[i - 1][j] == 1)
                        cnt++;
                }
            }
        }

        return cnt;
    }
}