I have two identical maps, except that one is printed as A3 and one is A4. I rotate the A4 map 45 degrees anti-clockwise and position it over the A3 such that the top left corner of the A4 map lies on the left edge of the A3 map, and the bottom left corner of the A4 map lies on the bottom edge of the A3 map.

There will be exactly one point such that if I put a pin through the two maps, they will pinpoint the same place on the map. Where should I put the pin?