CF1257C.Dominated Subarray

Let's call an array $t$ dominated by value $v$ in the next situation.

At first, array $t$ should have at least $2$ elements. Now, let's calculate number of occurrences of each number $num$ in $t$ and define it as $occ(num)$ . Then $t$ is dominated (by $v$ ) if (and only if) $occ(v) > occ(v')$ for any other number $v'$ . For example, arrays $[1, 2, 3, 4, 5, 2]$ , $[11, 11]$ and $[3, 2, 3, 2, 3]$ are dominated (by $2$ , $11$ and $3$ respectevitely) but arrays $[3]$ , $[1, 2]$ and $[3, 3, 2, 2, 1]$ are not.

Small remark: since any array can be dominated only by one number, we can not specify this number and just say that array is either dominated or not.

You are given array $a_1, a_2, \dots, a_n$ . Calculate its shortest dominated subarray or say that there are no such subarrays.

The subarray of $a$ is a contiguous part of the array $a$ , i. e. the array $a_i, a_{i + 1}, \dots, a_j$ for some $1 \le i \le j \le n$ .

The first line contains single integer $T$ ( $1 \le T \le 1000$ ) — the number of test cases. Each test case consists of two lines.

The first line contains single integer $n$ ( $1 \le n \le 2 \cdot 10^5$ ) — the length of the array $a$ .

The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \le a_i \le n$ ) — the corresponding values of the array $a$ .

It's guaranteed that the total length of all arrays in one test doesn't exceed $2 \cdot 10^5$ .

Print $T$ integers — one per test case. For each test case print the only integer — the length of the shortest dominated subarray, or $-1$ if there are no such subarrays.

In the first test case, there are no subarrays of length at least $2$ , so the answer is $-1$ .

In the second test case, the whole array is dominated (by $1$ ) and it's the only dominated subarray.

In the third test case, the subarray $a_4, a_5, a_6$ is the shortest dominated subarray.

In the fourth test case, all subarrays of length more than one are dominated.