No. 1 is in the thread somewhere below. I remember this one that I have read somewhere decades ago:
Write a program which if number "1" is in the display (X register) would turn it into "2", and if the number "2" is there it will turn it into "1", in as few as possible steps, without using numeric, EEX or CHS keys.
There was a solution in 3 steps, say:
LBL A: ... : ... : ... : RTN