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You have a large pile of ropes and some matches. All you know about the ropes:

  • Each rope has a different length
  • Each rope burns completely (starting from one end) in exactly 64 minutes
  • Each rope has non-uniform density, meaning it is thicker at some points than others. Consequently, burning half a rope cannot be guaranteed to take 32 minutes.

The goal is to identify when exactly 63 minutes have passed.