Binary Search First Occurrence

using System;

class Program {
	static void Main() {
		int[] arr = new int[] { 1, 2, 4, 4, 4, 7, 9 };
		int target = 4;
		int lo = 0;
		int hi = arr.Length - 1;
		int result = -1;
		while (lo <= hi) {
			int mid = lo + (hi - lo) / 2;
			if (arr[mid] == target) {
				result = mid;
				hi = mid - 1;
			} else if (arr[mid] < target) {
				lo = mid + 1;
			} else {
				hi = mid - 1;
			}
		}
		Console.WriteLine(result);
	}
}