0
+
0
=
0
0
+
1
=
1
0
+
2
=
2
0
+
3
=
3
0
+
4
=
4
0
+
5
=
5
0
+
6
=
6
0
+
7
=
7
0
+
8
=
8
0
+
9
=
9