EDITED: The figures below now give the surgery sequence starting with three curves and ending with one. [![surface with three curves and one surgery arc][1]][1] [![surface with two curves and one surgery arc][2]][2] [![surface with one curve][3]][3] [1]: https://i.sstatic.net/rJp0U.png [2]: https://i.sstatic.net/F3Zpk.png [3]: https://i.sstatic.net/uBtSD.png