lowerDate=datetime.now() - timedelta(days=daysToLookBackupL)
		upperDate=datetime.now()
		responseLatest = ddb.list_backups(TableName=ddbTable, TimeRangeLowerBound=datetime(lowerDate.year, lowerDate.month, lowerDate.day), TimeRangeUpperBound=datetime(upperDate.year, upperDate.month, upperDate.day))
		latestBackupCount=len(responseLatest['BackupSummaries'])
		print('Total backup count in recent days:',latestBackupCount)

		if latestBackupCount>=2:
			deleteupperDate = datetime.now() - timedelta(days=daysToLookBackup)
			response = ddb.list_backups(TableName=ddbTable, TimeRangeLowerBound=datetime(2017, 11, 29), TimeRangeUpperBound=datetime(deleteupperDate.year, deleteupperDate.month, deleteupperDate.day))

			while True:
				for record in response['BackupSummaries']:
					backupArn = record['BackupArn']
					ddb.delete_backup(BackupArn=backupArn)
					print(backupName, 'has deleted this backup:', backupArn)
				if 'LastEvaluatedBackupArn' in response:
					lastEvalBackupArn = response['LastEvaluatedBackupArn']
					response = ddb.list_backups(TableName=ddbTable, TimeRangeLowerBound=datetime(2017, 11, 29), TimeRangeUpperBound=datetime(deleteupperDate.year, deleteupperDate.month, deleteupperDate.day), ExclusiveStartBackupArn=lastEvalBackupArn)
				else:
					lastEvalBackupArn = ''
					print ('the end')
					break
		else:
			print ('Recent backup does not meet the deletion criteria, because the latestBackupCount is ' + str(latestBackupCount))