In the grid below, four of the sixteen cells will remain blank. The remaining twelve will have the letters, A, B, C, D, E and F, each repeated twice: once underlined and once not. Four of these letters have already been placed, three underlined and one not.

Fill in the remaining letters, underlined or not as appropriate, using the following rules:

1. Identical letters may not occupy the same row, column or diagonal.
2. In both cases, A and E of opposite formats (underlined and not) share a diagonal of some length.
3. Each B is vertically directly between two of the blank cells.
4. All the letters placed in the bottom row are to be underlined.

	F
	C	E	B

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From Mensa Puzzle Calendar 2017 by Mark Danna and Fraser Simpson, Workman Publishing, New York. Puzzle for October 27.