What's the longest butterfly race you could swim?

Could swim, would swim, or want to swim? I could swim a 100 (if absolutely necessary), only want to swim 50 or less, and would do everything possible to get out of swimming the 100.

Could swim, would swim, or want to swim? I could swim a 100 (if absolutely necessary), only want to swim 50 or less, and would do everything possible to get out of swimming the 100.