Substring and If then Condition to create column

[Chandan]

Hi There,

I have a requirement to create a new column by classifying the roads as Main roads and local roads.
If Road_No starting with H or M I want to classify it as Main roads, if not then local roads.

Below is the column name and the road numbers:
Road_No

H001
H0002
M002
M03050
A001
B002
C002
F002
5001
8002

Appreciate if you can assist me with this.
Kind regards,
CK