You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Nikola_Tesla

Context:
Tesla obtained around 300 patents worldwide for his inventions. Some of Tesla's patents are not accounted for, and various sources have discovered some that have lain hidden in patent archives. There are a minimum of 278 patents issued to Tesla in 26 countries that have been accounted for. Many of Tesla's patents were in the United States, Britain, and Canada, but many other patents were approved in countries around the globe.:62 Many inventions developed by Tesla were not put into patent protection.

Question:
In how many countries did Tesla hold patents?

26