If the image placed inside a folder has numeric file name, its not taking it as valid file name

[Dude]

hi,
images=("C:\images\1.png","C:\images\2.png")
icon = ["Setting","Schedule","Vacation","Weather"]
for img in images:

    if exists(img,0): print "exists"
    else: print "not found"

For this piece of code, its not finding the match even if it available on the screen.
it printing "not found"
and am getting a error message, as following.
[error] C:\images.png looks like a file, but can't be found on the disk. Assume it's text.

But when change that filename as "icon1.png" and "icon2.png", it works fine.