You should also know that in Python, iterating over integer indices is bad style, and also slower than the alternative. If you just want to look at each of the items in a list or dict, loop directly through the list or dict.

mylist = [1,2,3]
for item in mylist:
    print item

mydict  = {1:'one', 2:'two', 3:'three'}
for key in mydict:
    print key, mydict[key]

This is actually faster than using the above code with range(), and removes the extraneous i variable.

If you need to edit items of a list in-place, then you do need the index, but there's still a better way:

for i, item in enumerate(mylist):
    mylist[i] = item**2

Again, this is both faster and considered more readable. This one of the main shifts in thinking you need to make when coming from C++ to Python.

You wrote

for i in timestoprint:
    printHello()

instead of

for i in range(timestoprint):
    printHello()

You also forgot to convert timestopprint to an int

This works for me:

timestoprint = int(input("How many times to print hello?"))

for i in range(timestoprint):
    print("hello")

There seems to be a few things you may want to fix in your code:

1. Do not use int as variable name. It has a special meaning in Python and this name should never be used in other ways.
2. If you expect user to input a bunch of numbers you cannot directly cast input to int. It depends on how the numbers will be inputed but you first need to separate them from input string (initially input returns strings). That's what's causing your error. Look at the previous answers for examples.
3. The logic of your function could use some improvement. If you want to return smallest, non-negative element from your list there is no need to first filter them to separate list.

it's because "%d" is used for string formatting and it returns string only:

In [18]: type( "%d" % 3)
Out[18]: <type 'str'>

use just ,range(0,4) or xrange(0,4) if you're on python 2.x:

In [19]: range(0,4)  #0 is the default value of the first argument, so range(0,4)==range(4)
Out[19]: [0, 1, 2, 3]