Given a sorted list of numbers and a target Z, return the number of pairs according to following definition: (X,Y) where X+Y >= Z\n\n**Example 1:**\n```\nInput: arr = [1, 3, 7, 9, 10, 11], Z = 7\nOutput: 14\n```\n\n<details> \n  <summary>My java solution</summary>\n\n```java\npublic static int countPairs(int[] arr, int target) {\n    int count = 0;\n    for (int lo = 0, hi = arr.length - 1; lo < hi; ) {\n        if (arr[lo] + arr[hi] >= target) {\n            count += hi - lo;\n            hi--;\n        } else  {\n            lo++;\n        }\n    }\n    return count;\n}\n```\n</details>

Given a sorted list of numbers and a target Z, return the number of pairs according to following definition: (X,Y) where X+Y >= Z\n\nExample 1:\n\nInput: arr = 