Col A contains:
1
5
7
10
14

Col B contains:
2
3
6

Col C contains:
4
6
8
11
13

Col D contains:
1
5
8
9
10
12
13
14
15

How do I put, in Col E, each number from the FIRST column it occurred
in:
1 (came from Col A)
2 (came from Col B)
3 (came from Col B)
4 (came from Col C)
5 (came from Col A)
6 (came from Col B)
7 (came from Col A)
8 (came from Col C)
9 (came from Col D)
10 (came from Col A)
11 (came from Col C)
12 (came from Col D)
13 (came from Col C)
14 (came from Col A)
15 (came from Col D)