length n is known as a palindrome if the uniformity t[i]=t[n−i+1] is valid for all I (1≤i≤n). For instance, on the off chance that s="01?????0", a=4 and b=4, you can supplant the characters '?' in the accompanying ways: "01011010"; "01100110".
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string t of length n is known as a palindrome if the uniformity t[i]=t[n−i+1] is valid for all I (1≤i≤n).
For instance, on the off chance that s="01?????0", a=4 and b=4, you can supplant the characters '?' in the accompanying ways:
"01011010";
"01100110".
For the given string s and the numbers an and b, supplant every one of the characters with '?' in the string s by '0' or '1' so the string turns into a palindrome and has precisely a characters '0' and precisely b characters '1'.
Input
The principal line contains a solitary integer t (1≤t≤104). Then, at that point, t experiments follow.
The main line of each experiment contains two integers an and b (0≤a,b≤2⋅105, a+b≥1).
The second line of each experiment contains the string s of length a+b, comprising of the characters '0', '1', and '?'.
It is ensured that the amount of the string lengths of s over all experiments doesn't surpass 2⋅105.
Output
For each experiment, output:
"- 1", if you can't supplant every one of the characters '?' in the string s by '0' or '1' so the string turns into a palindrome and that it contains precisely a characters '0' and precisely b characters '1';
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