Print alphabetical order with awk

$ for i in $(seq 10); do echo $i; done | awk 'BEGIN {split("ABCDEFGHIJKLMNOPQRSTUVWXYZ", A, "")}{print $0, A[$0]}'
1 A
2 B
3 C
4 D
5 E
6 F
7 G
8 H
9 I
10 J