Easy Approach !
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\n  int findMaxK(List<int> nums) {\n    nums.sort();\n    for(int i=nums.length-1 ; i>=0 ; i--){\n        if(nums[i]>0 && nums.contains(-nums[i])){\n            return nums[i];  \n        }else if(nums[i]<0){\n            return -1;\n        }\n    }\n    return -1;\n  }\n}\n```
['Dart']