finding the minimum value out of a set of inputs

[ichabod801]

The reason your loop goes on forever is that you never change either string or i in the loop. So the condition in the while statement never changes.

While another value has been read successfully

This says to me that you want to get a new input each time through the loop. But you don't have an input inside the loop. You need one inside the loop, so you have a changing value for your while condition. However, it seems from the question in the input that the while condition should be looking for -1. I think the pseudocode it talking about this kind of structure:

answer = input('Keep going? ')
while answer != 'no':
    print('okay')
    answer = input(Keep going? ')