Bring back row and column value based on the number in a cell

[Supe]

I have a spreadsheet that has the store numbers going across the columns and
the UPC numbers down the rows. I need to create a separate sheet that if the
value in a cell is 1, the first column of the sheet will show the store
number of the column and the UPC number of that row that the 1 is in.

For the example below, store #7704 and UPC 1583900006 meet the criteria of 1
in that cell. My result on the separate sheet would then be 7704 in cell A1
and 158390006 in cell B1

Item Master UPC/PLU/SLU 7703 7704
1583900001 222 222
1583900002 222 X
1583900003 222 222
1583900006 222 1


I have over 100 rows and over 300 columns so trying to find a more efficient
way of doing this other than manual entry. Thanks.