Detailed Instructions: This task involves creating questions from a given passage that involve some kind of complex reasoning (including numerical reasoning).
The generated questions must require looking at more than one part of the passage to answer. Try to use a variety of reasoning types in your questions (some of the sample reasoning types are illustrated in the 'positive examples' field) and also have a variety of answer types (spans, numbers, dates). A span is a continuous phrase taken directly from the passage or question. In such questions, the answer spans are recommended to be five words. Questions with answer type "number", are expected to start with "How many". For instance, "How long did an event last?" can be phrased as "How many years did an event last?". To increase diversity, try to create more questions for which the answer will be multiple spans. Please create questions that require AT LEAST 2 arithmetic operations as illustrated in the 'positive examples' field. You are encouraged to try DIFFERENT COMBINATIONS of operations and not just limit to the combinations shown in those examples. The more challenging questions you create, the better it is.
Q: Passage: Exceptions to this claimed general rule were the Lancastrian looting of Ludlow after the largely bloodless Yorkist defeat at Ludford Bridge in 1459, and the widespread pillaging carried out by Queen Margaret's unpaid army as it advanced south in early 1461. Both events inspired widespread opposition to the Queen, and support for the Yorkists. Many areas did little or nothing to change their city defences, perhaps an indication that they were left untouched by the wars. City walls were either left in their ruinous state or only partially rebuilt. In the case of London, the city was able to avoid being devastated by convincing the York and Lancaster armies to stay out after the inability to recreate the defensive city walls. Few noble houses were extinguished during the wars; in the period from 1425 to 1449, before the outbreak of the wars, there were as many extinctions of noble lines from natural causes as occurred during the fighting from 1450 to 1474. The most ambitious nobles died and by the later period of the wars, fewer nobles were prepared to risk their lives and titles in an uncertain struggle. The kings of France and Scotland and the dukes of Burgundy played the two factions off against each other, pledging military and financial aid and offering asylum to defeated nobles and pretenders, to prevent a strong and unified England from making war on them.
A:
After being unable to recreate the defensive city walls, the city of London was able to convince which armies to stay out, Burgundy armies or the York armies?