PLEASE HELP ME

i entered the following formula in cell k7 :
=CHOOSE(MATCH("X",F7:F7:F7,0),5)

which means :f there is the letter X in cell F7, then give me the answer 5.

SO NOW....WHAT SHOULD I DO IN ORDER TO HAVE THE FOLLOWING ORDER :

f there is the letter X in cell F7, then give me the result 5 , and if
there is the letter Y give me the result 6 ????

THANKS