Please,I need help with this Alphabet, number conversion.

Suppose we define f(A)=1,f(a)=-1,f(B)=2,f(b)=-2,...f(Z)=26,f(z)=-26; Based on this relation, enter an alphabet letter(x)('A'..'Z' or 'a'..'z') and an integer(y), calculate on f(x)+y。 https://code.sololearn.com/cm5haL7aO9n6/?ref=app