Performing arithmetic on Ruby String variable

I have a ruby string variable that can have the value 1.10.2.ab2-4.cl6 or 1.11.2.ab2-4.dl5 or 1.13.2.ab2-4.el6

I want to take the first two integer values of this variable which could be 1.10 or 1.11 or 1.13 and then print hello if the value is < 1.13