Roy is looking for Wobbly Numbers.

An N-length wobbly number is of the form "ababababab..." and so on of length N, where a != b.

A 3-length wobbly number would be of form "aba".
Eg: 101, 121, 131, 252, 646 etc
But 111, 222, 999 etc are not 3-length wobbly number, because here a != b condition is not satisfied.
Also 010 is not a 3-length wobbly number because it has preceding 0. So 010 equals 10 and 10 is not a 3-length wobbly number.

A 4-length wobbly number would be of form "abab".
Eg: 2323, 3232, 9090, 1414 etc

Similarly we can form a list of N-length wobbly numbers.

Now your task is to find K^th wobbly number from a lexicographically sorted list of N-length wobbly numbers. If the number does not exist print -1 else print the K^th wobbly number. See the sample test case and explanation for more clarity.

Input:
First line contains T - number of test cases
Each of the next T lines contains two space separated integers - N and K.

Output:
For each test case print the required output in a new line.

Constraints:
1 ≤ T ≤ 100
3 ≤ N ≤ 1000
1 ≤ K ≤ 100

SAMPLE INPUT
6
3 1
3 2
3 100
4 3
4 4
5 2

SAMPLE OUTPUT
101
121
-1
1313
1414
12121

Explanation

First 10 terms of 3-length wobbly numbers arranged lexicographically is as follows:
101, 121, 131, 141, 151, 161, 171, 181, 191, 202

1st wobbly number of length 3 is 101.
2nd wobbly number of length 3 is 121.
100th wobbly number of length 3 does not exist, so the output is -1.

First 10 terms of 4-length wobbly numbers arranged lexicographically is as follows:
1010, 1212, 1313, 1414, 1515, 1616, 1717, 1818, 1919, 2020

3rd wobbly number of length 4 is 1313.
4th wobbly number of length 4 is 1414.

Similarly 2nd wobbly number of length 5 is 12121

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