Instead of doing all those empty PRINTs, try using variables.
-Replace Line 1 with X=4
-On Line 11, replace the 4 with X
-Remove everything below Line 14
-Replace Lines 12 and 13 with
IF B==1 THEN DEC X
IF B==2 THEN INC X
-Replace Line 9 with WHILE 1 and Line 14 with WEND
-Add VSYNC 1 between Lines 9 and 10
-Replace BUTTON(3) with BUTTON(1)
Hope this helped!