https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/\n\nGiven a string `str` consisting of parentheses `(`, `)` and alphanumeric characters. Remove minimum number of paranthesis to make the string valid and return **any** valid result. In a valid string for every opening/closing parentheses there is a matching closing/opening one.\n\n**Example 1:**\n```\nInput: "ab(a(c)fg)9)"\nOutput: "ab(a(c)fg)9" or "ab(a(c)fg9)" or "ab(a(cfg)9)"\n```\n\n**Example 2:**\n```\nInput: ")a(b)c()("\nOutput: "a(b)c()"\n```\n\n**Example 3:**\n```\nInput: ")("\nOutput: ""\n```\n\n**Example 4:**\n```\nInput: "a(b))"\nOutput: "a(b)"\n```\n\n**Example 5:**\n```\nInput: "(a(c()b)"\nOutput: "a(c()b)" or "(ac()b)" or "(a(c)b)"\n```\n\n**Example 6:**\n```\nInput: "(a)b(c)d(e)f)(g)"\nOutput: "(a)b(c)d(e)f(g)"\n```\n\nRelated problems:\n* https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/\n* https://leetcode.com/problems/remove-invalid-parentheses is a **different** problem, becuase in this case we need to return only 1 result

https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/\n\nGiven a string str consisting of parentheses (, ) and alphanumeric characters. Remove