Twisted Circuit
说明
E. Twisted Circuit
time limit per test
2 secondsmemory limit per test
64 megabytesinput
standard inputoutput
standard output
Input
The input consists of four lines, each line containing a single digit 0 or 1.
Output
Output a single digit, 0 or 1.
Example
Input
0
1
1
0
Output
0
样例
