You are given two integers (n) and (k). Construct a binary string(^{\text{∗}}) (s) of length (n), such that both of the following conditions hold: The absolute difference between the number of characters (\mathtt{0}) and the number of characters (\mathtt{1}) in (s) is at most (1). There are exactly (k) pairs of adjacent equal characters in (s). Formally, there are exactly (k) indices (i) ((1 \le i \le n-1)) satisfying (s_i = s_{i + 1}). Or determine that no such string exists. (^{\text{∗}})A binary string is a string where each character is either (\mathtt{0}) or (\mathtt{1}). Each test contains multiple test cases. The first line contains the number of test cases (t) ((1 \le t \le 1000)). The description of the test cases follows. The only line of each test case contains two integers (n) and (k) ((2 \le n \le 2 \cdot 10^5), (0 \le k \le n-1)). It is guaranteed that the sum of (n) over all test cases does not exceed (2 \cdot 10^5). For each test case, output a binary string (s) of length (n) — the string you constructed. Print (-1) if such a string does not exist. If there are multiple answers, you may output any of them. In the first test case, one possible answer is (s=\mathtt{01110}). It contains three characters (\mathtt{1}) and two characters (\mathtt{0}), and there are exactly (2) adjacent equal pairs in (s): ((s_2, s_3)) and ((s_3, s_4)). In the second test case, (k=n-1). All characters in (s) should be equal, so the numbers of characters (\mathtt{0}) and (\mathtt{1}) could not differ by at most (1). Thus, the answer is (-1). In the third test case, note that (\mathtt{010110}) is also a possible answer.