Inputs a value 'a' and a number 'd', and using only the number any number of times, it must equate to the value.
For eg,a=7,d=4; Expression:- (4+4+4)÷4+4=7
or a=14,d=5; Expression:- ((5+5+5)x5-5)÷5=14
This java file implements recursion and backtracking to solve the problem.