Given a range L to R, the task is to find the highest occurring digit in prime numbers which lie between L and R (both inclusive). If multiple digits have same highest frequency print the largest of them. If no prime number occurs between L and R, output -1.

**Input:**

The first line of input contains T denoting number of test cases. The only line of each test case contains two integers L and R, denoting the range.

**Output:**

For each test case output a single line containing the answer.

**Constraints:**

1<= T <= 5000

2<= L<=R <= 10^6

R-L<=10^4

**Example:
Input:**

2

2 10

2 20

**Output:**

7

1

**Explanation:**

Prime number between 2 and 20 are 2, 3, 5, 7, 11, 13, 17, 19. 1 occur maximum i.e 5 times among 0 to 9.

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