Filtering by First Value in a String?

Hello,

I have a field that pulls contract numbers but we only need ones that start with a C or a V.

I am trying to use a formula filter with the formula  LEFT([Field],1)="c" .or. "v" , but it is giving me an error.

Examples of the contract numbers that are pulled are B687458, C786545, G789545, and V789545. What would be a formula I could use in either a filter or calculated field to give me these results?

Thank you,

Kris