public int getColumnCount(String sheetName){
		// check if sheet exists
		if(!isSheetExist(sheetName))
		 return -1;
		
		sheet = workbook.getSheet(sheetName);
		row = sheet.getRow(0);
		
		if(row==null)
			return -1;
		
		return row.getLastCellNum();
		
		
		
	}