Problem Statement

You are given an array nums containing positive integers. A nums array is special if there exists a number x such that there are exactly x elements of the array greater than or equal to x.

Return the value of x if the array is special. Otherwise, return -1.

Note: The array may or may not contain the x.

Examples

Example 1:

• Input: [3, 5, 3, 4]
• Expected Output: -1
• Justification: There's no value X from 1 to 4 such that there are exactly X elements greater than or equal to X.

Example 2:

• Input: [0, 5, 2, 4, 3]
• Expected Output: 3
• Justification: There are 3 elements (5, 4, 3), which are greater than or equal to 3 in the nums array.

Example 3:

• Input: [5, 6, 7, 8, 9]
• Expected Output: 5
• Justification: Each number in the array is greater than or equal to 5, and since there are 5 elements in total, 5 is the special value.

Try it yourself

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