You are given a string S of 2N characters consisting of N ‘[‘ brackets and N ‘]’ brackets. A string is considered balanced if it can be represented in the for S2[S1] where S1 and S2 are balanced strings. We can make an unbalanced string balanced by swapping adjacent characters. Calculate the minimum number of swaps necessary to make a string balanced.
Note - Strings S1 and S2 can be empty.
Input : ][ Output : 2 Explanation : First swap: Position 3 and 4 ][ Second swap: Position 5 and 6 
Input : [] Output : 0 Explanation: String is already balanced.
You don't need to read input or print anything. Your task is to complete the function minimumNumberOfSwaps() which takes the string S and return minimum number of operations required to balance the bracket sequence.
Expected Time Complexity: O(N).
Expected Auxiliary Space: O(1).
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