F. ⅓ оf а Рrоblеm
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

$$$$$$a\qquad \mathord{4}\qquad \mathord{+}\qquad \mathord{-}\qquad \mathord{+}\qquad \mathord{-}\qquad \mathord{)}\qquad \mathord{2}$$$$$$

Example
Input
0 1
Output
0