请看下列代码:(     )

class Inner {
    private int x;
    public void setX(int x) {this.x = x; }
    public int getX() { return x;}
}
class Outer {
    private Inner y;
    public void setY(Inner y) {this.y = y;}
    public Inner getY() { return y;}
}
public class Gamma {
    public static void main(String[] args) {
        Outer o = new Outer();
        Inner i = new Inner();
        int n = 10;
        i.setX(n);
        o.setY(i);
        <插入代码>
        System.out.println(o.getY().getX());
    }
}

运行上述代码，要求输出“100”，那么<插入代码>处应填入的代码是：