1
1
2
1
3
+
1
1
2
1
3
+
1
4
1
5
1
6
1
7
1
1
2
1
3
+
1
4
1
5
+
1
6
1
7
+
2
1
2
etc ...
1
2
1
2
1
2
1
1
0
1
0
1
0
1
0
1
y =
1
x
1
1
2
1
3
+
3
2
2
3
(
,
)
5
4
4
5
(
,
)
7
4
4
7
(
,
)
+
+