you give stre num represent large integer an integer good meet follow conditionsIt substre num length 3it consist unique digitReturn maximum good integer string string integer existsnotea substre contiguous sequence character stringthere lead zeroes num good integer Example 1input num 6777133339output 777explanation there distinct good integer 777 333777 large return 777example 2input num 2300019output 000explanation 000 good integerExample 3input num 42352338output Explanation no substre length 3 consist unique digit therefore good integer Constraints3 numlength 1000num consist digit