First Negative Index Programming Challenge

Problem

Find the position (counting from 0) of the first negative number in the list.

Implement first_negative_index(numbers).

numbers: The list of integers.

Return the index, or -1 if there are no negative numbers.

0 ≤ length ≤ 100,000

Example 1

Input:
numbers = [4, 0, -2, -7]

Expected output:
expected = 2

Input:
std::vector<long long> numbers = {4, 0, -2, -7};

Expected output:
long long expected = 2;

Input:
long[] numbers = new long[] {4, 0, -2, -7};

Expected output:
long expected = 2;

-2 at index 2 is the first negative value.

Example 2

Input:
numbers = [1, 2, 3]

Expected output:
expected = -1

Input:
std::vector<long long> numbers = {1, 2, 3};

Expected output:
long long expected = -1;

Input:
long[] numbers = new long[] {1, 2, 3};

Expected output:
long expected = -1;

There are no negative numbers, so the answer is -1.

This challenge is adapted for CodeUtility. Follow the statement and constraints above.