u
2
0
v
2
0
w
2
0
x
2
0
y
1
4
2
0
+
1
2
0
+
1
2
0
+
1
2
0
+
1
1
4
=
2
2
6
4
8
5
4
1
1
2
9
6
1
≈
2
0
.
0
4
9
8
7
5
6
2
0
8