How to seperate numbers from a string variable

I have a string variable that has labels and a number. I only need the number. How do I separate it out? This is an example.

Code:

clear
input str30 IfindImmunologicalconceptsdi
"(4) Agree"                     
"(4) Agree"                     
"(5) Strongly Agree"            
"(2) Disagree"                  
"(4) Agree"                     
"(2) Disagree"                  
"(4) Agree"                     
"(2) Disagree"                  
"(5) Strongly Agree"            
"(4) Agree"                     
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(3) Neither Agree nor Disagree"
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(2) Disagree"                  
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(4) Agree"                     
"(2) Disagree"                  
"(2) Disagree"                  
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(4) Agree"                     
"(4) Agree"                     
"(3) Neither Agree nor Disagree"
"(2) Disagree"                  
"(4) Agree"                     
"(4) Agree"                     
"(3) Neither Agree nor Disagree"
"(4) Agree"                     
"(4) Agree"                     
"(2) Disagree"                  
"(4) Agree"                     
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(3) Neither Agree nor Disagree"
"(4) Agree"                     
"(2) Disagree"                  
"(4) Agree"                     
end