In the paper, the 3 bottom photos in Figure 2(a) were the same as the 3 bottom photos in Figure 2(b), and here we provide the right form of Figure 2(a). We apologize for this oversight and for any confusion that it has caused.

In the paper, the 3 bottom photos in Figure 2(a) were the same as the 3 bottom photos in Figure 2(b), and here we provide the right form of Figure 2(a). We apologize for this oversight and for any confusion that it has caused.
