int[] x = {1,2};
int[] y = java.util.Arrays.copyOf(x, x.length);
y[0] = 9;
System.out.println(x[0]);

import java.util.*;
List<Integer> list = new ArrayList<>(java.util.Arrays.asList(1,2,3));
for (Integer v : list) {
  if (v == 2) list.remove(v);
}
System.out.println(list.size());

StringBuilder sb = new StringBuilder("a");
String s = sb.toString();
sb.append("b");
System.out.println(s);

char c = 'A';
c += 2;
System.out.println(c);

int s = 0;
for (int i = 1; i <= 4; i++) {
  if (i % 2 == 1) continue;
  s += i;
}
System.out.println(s);