I don't know where the numbers in that diagram come from, but in generic boards the pins to number relation is straight PA0-15, then PB0-15 and so, except not all pins are available in all MCUs. The numbers are not skipped, instead the next consecutive number is used for the next consecutive exiting pin. They are in an enum:
https://github.com/rogerclarkmelbourne/ ... rd/board.h
Since none of them is assigned a value, the compiler will start from 0 for PA0.
To avoid confusion, always use PA0, PA1 etc in your sketches, since 0 in a maple mini corresponds to a different pin than a bluepill, and that may correspond to something else in another board.
About your pin selection, both inputs need to be Ch1 and Ch2 of the same timer.
PA10 and PB3 are different timers, and on top PA10 is Channel 3 of that particular timer.
Correct me if I'm wrong, but according to the reference manual, you need to use inputs 1 and 2.
In the diagram, PA8 and PA9 are Ch1 and 2 of the same timer, try those 2.