How to make my path relative in selenium apache poi while I input my Excel file? and How to write the test result in excel after performing testing

FileInputStream input=new FileInputStream(new File("C:\\Report\\TestCase.xls"));
HSSFWorkbook workbook=new HSSFWorkbook(input);
HSSFSheet sheet=workbook.getSheet("KeywordFramework");
System.out.println("i am in");

How can i make my path a relative path ? Example (..\..\TestCase.xls) It should search the file in system and call it , is the requirement

HSSFWorkbook workbook=new HSSFWorkbook(input);
  ExpectedOP=Cellvalue;
    int LastRow = 1;
        for(int i1=1;i1<5;i1++)
        {
        String sr [] =new String [10];
        sr[i1]=driver.findElement(By.xpath(".//*[@id='stepList']/li["+i1+"]")).getText();
        System.out.println("UserID = "+sr[i1]);
        for (int j1=1;j1<sr.length;j1++)
            {
            if(ExpectedOP.equals(j1))
            {
                System.out.println("compare pass");
                String status="PASS";
                Row row1 = sheet.getRow(LastRow);

                Cell cell2 = row1.createCell(18);
                cell2.setCellValue(status);
                System.out.println(status);

                input.close();
                FileOutputStream outFile =new FileOutputStream(new File("TestCase.xls"));
                workbook.write(outFile);
            }
            else
            {
            System.err.println("compare fail");
            String status = "FAIL";
            Row row1 = sheet.getRow(LastRow);

            Cell cell2 = row1.createCell(18);
            cell2.setCellValue(status);
            System.out.println(status);

            input.close();
            FileOutputStream outFile =new FileOutputStream(new File("TestCase.xls"));
            workbook.write(outFile);
            }
            }
        }

This is my code to compare value from website and excel and here am telling IDE to place the pass/fail result in cell number 18 , which i want to make dynamic and also in "i1<5" "5" should be removed and made dynamic which number of cell counts Thank you