Shortest Subarray with at Least K Distinct Integers

You are given an array of n integers and an integer k. Your task is to determine the length of the shortest contiguous subarray that contains at least $k$ distinct integers. If no such subarray exists, output -1.

Note: The value k can be any integer. Use efficient algorithms to avoid timeout on larger inputs.

The problem can be formally stated as follows:

Given an array A of length n and an integer k, find the minimal length L such that there exists an index i and j with 0 ≤ i ≤ j < n for which the subarray A[i...j] contains at least $k$ distinct numbers. If no such L exists, print -1.

inputFormat

The input is provided via standard input (stdin) and has the following format:

n k
A0 A1 ... An-1

Where:

• n is the number of elements in the array.
• k is the minimum number of distinct integers required in the subarray.
• The second line contains n space-separated integers representing the array.

outputFormat

The output is a single integer printed to standard output (stdout). This integer is the length of the shortest contiguous subarray that contains at least $k$ distinct integers. If no valid subarray exists, output -1.

## sample

7 3
1 2 1 2 3 4 5

3