Your task is to write a program that reads a natural number and prints the sum of their
three last digits.
The input is a natural number n≥100.
The output is a line with the sum of the last three digits of n.
The official statement of a problem is always the one
in the PDF document. The HTML and PNG versions of the statement
are also given to help you, but they may contain some content
that is not well displayed. In case of doubt, always use the PDF.