import java.util.*;
public class MyClass {
public static int TOTAL_BITS = 8;
public static void set_random_bits(BitSet sb) {
Random r = new Random();
for (int i = 0; i < TOTAL_BITS / 2; i++)
sb.set(r.nextInt(TOTAL_BITS));
}
public static void print_bits(BitSet sb) {
for (int i = 0; i < TOTAL_BITS; i++) {
System.out.print(sb.get(i) ? "1" : "0");
}
System.out.println();
}
public static void main(String args[]) {
BitSet bs = new BitSet(TOTAL_BITS);
set_random_bits(bs);
print_bits(bs);
bs.flip(0, 4);
print_bits(bs);
}
}
/*
run:
01000110
10110110
*/