quiz time guys
choose the odd one out
1) 12839/40 howrah-chennai sf mail
12841/42 coromandal sf exp
2) 12151/52 samarsata sf exp
...
more... 12101/02 jnaneswari sf exp
3) 18645/46 east coast exp
18615/16 howrah-hatia exp
4) 22811/12 bhubaneswar rajdhani exp (via adra)
22823/24 bhubaneswar rajdhani exp (via tata)
the question is related about coach composition.