Chef is playing a variant of Blackjack, where 3 numbers are drawn and each number lies between 1 and 10 (with both 1 and 10 inclusive). Chef wins the game when the sum of these 3 numbers is exactly 21.

Given the first two numbers A and B, that have been drawn by Chef, what should be 3-rd number that should be drawn by the Chef in order to win the game?

Note that it is possible that Chef cannot win the game, no matter what is the 3-rd number. In such cases, report -1 as the answer.

------ Input Format ------

• The first line will contain an integer T - number of test cases. Then the test cases follow.
• The first and only line of each test case contains two integers A and B - the first and second number drawn by the Chef.

------ Output Format ------

For each testcase, output the 3-rd number that should be drawn by the Chef in order to win the game. Output -1 if it is not possible for the Chef to win the game.

------ Constraints ------

$1 ≤ T ≤ 100$
$1 ≤ A, B ≤ 10$

----- Sample Input 1 ------
3
1 10
1 5
4 9
----- Sample Output 1 ------
10
-1
8
----- explanation 1 ------
Test case $1$: The first two numbers are $1$ and $10$. If the third number will be $10$, the resulting sum will be $1 + 10 + 10 = 21$. So Chef will win the game if the third number is $10$.

Test case $2$: The first two numbers are $1$ and $5$. There is no number between $1$ and $10$, that can make the resulting sum $21$. Hence, the answer will be $-1$ in this test case.

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