public static boolean s(int[][] m, int x, int y) {
		boolean ans = true;
		int c1 = 0, c2 = 0, aux = 0;
		if (x != -1 && y != -1) {
			aux = m[x][y];
			m[x][y] = Math.abs(m[x][y] - 1);
		}
		for (int i = 0; i < m.length; i++) {
			c1 = c2 = 0;
			for (int j = 0; j < m.length; j++) {
				c1 += m[i][j];
				c2 += m[j][i];
			}
			if (c1 % 2 == 1 || c2 % 2 == 1) {
				if (x != -1 && y != -1)
					m[x][y] = aux;
				return false;
			}
		}
		return ans;
	}