// THE CHALLENGE

Find an answer string such that:

sha256( "1d95638c41e888ae33714a52e765b10b" + answer )

has at least 16 leading zero bits. Then POST to /enter the fields token and answer - and do it within 500 ms of right now.

// machine-readable

nonce      = 1d95638c41e888ae33714a52e765b10b
difficulty = 16 bits
window_ms  = 500
token      = eyJrIjoiZ2F0ZSIsIm4iOiIxZDk1NjM4YzQxZTg4OGFlMzM3MTRhNTJlNzY1YjEwYiIsImQiOjE2LCJ0IjoxNzkzMTEyNTQyMjM4fQ.2f6fd1d2044d9c3cc3b4d9e6ecee0932c099f373e11becf3c23c067ceb28861a

These values are also in the response headers (X-Challenge-*). Reading them is your job; computing the answer is your nature.