If contains and if does not Contain a colon, select the number

I have an if statement that return the number if there is a colon symbol in the string, sometimes the string does not contain a colon symbol. I looking for a else statement that would select the only number "45061 if there is no colon in the string. A = Works when the string has a coloon sign but i need some assistance with B, if the string does not have a colon.

A.

String/Text = OM_Account_Master_Slave~Account CP~3712011:Shared-001

B.

String/Text = OM_Account_Master_Slave~Account CP~45061Shared-001

A. if(contains,":",Substring(Abbrev(),1,Subtract(Length(Abbrev()),11)))

Result = 3712011:Shared-001

B. if(contains,":",Substring(Abbrev(),1,Subtract(Length(Abbrev()),11))) else