public class Solution {
    public int HeightChecker(int[] heights) {
        int res = 0;
            int[] sortedHeights = new int[heights.Length];
            Array.Copy(heights,sortedHeights, heights.Length);
            Array.Sort(sortedHeights);
            for (int i = 0; i < heights.Length; i++)
            {
                if (sortedHeights[i] != heights[i])
                {
                    res++;
                }
            }
        return res;
    }
}