Code To Handle Negative Numbers

The below code looks in a certain column and deletes rows based on values less than the entered value in the input window. The problem with the code below is that it does not remove rows that have negative numbers. There is the possibility of a negative number being in the column so I would like to have that removed as well.

What would the code look like to add to the current code to remove the rows that have negative numbers? -1, -2, etc.

Sub Delete_Part_Input()
Dim Qty As Integer, i As Integer, ans As Variant

Qty = Application.InputBox("What total quantities would you like to delete? Note: This is the value located in the C column.", Type:=1)
If Qty = 0 Then Exit Sub

ans = MsgBox("All totals with a quantity of " & Qty & _
" or less will be deleted." & vbCrLf & vbCrLf & _.............