
You are given a 0-indexed integer array nums representing the score of students in an exam. The teacher would like to form one non-empty group of students with maximal strength , where the strength of a group of students of indices i _0 , i _1 , i _2 , ... , i _k is defined as nums[i _0 ] nums[i _1 ] nums[i _2 ] ... nums[i _k ​] .
Return the maximum strength of a group the teacher can create .
1 <= nums.length <= 13-9 <= nums[i] <= 9