Samu and Special Coprime Numbers problem from Hackerearth

Can any one explain the logic behind this question from hackerearth:

Samu had come up with new type of numbers, she named them Special Coprime numbers. Special Coprime numbers follow a property : A number N is said to be Special Coprime if sum of its digits as well as the sum of the squares of its digits are coprime to each other.

Now she started counting numbers that are Special Coprime. But soon she get bored and decided to write a program that can help do it. Now she want you to help her to find count of such numbers between L and R , where both L and R are included.

Input Format :
First line contain number of test cases T. Each test case contains two space separated integers L and R, denoting the range in which you need to find the count of Special Coprime numbers.

Output Format :
For each test case you need to print the count of such numbers in range [L,R]

Constraints :
1 ≤ T ≤ 10^3
1 ≤ L ≤ R ≤ 10^18

Question Link

General Approach to solve these type of Problems But unable to understand.

The above link shall explain you this kind of problems . Now for every question of this kind you need
to generalise them as F(l,r)=F(1,r)-F(1,l-1). I think you need to use the same here!

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