==========
1
+
1
 = 
2
==========
1
+
2
 = 
3
==========
2
+
3
 = 
5
==========
3
-
5
 = 
-2
==========
5
-
-2
 = 
7
==========
-2
-
7
 = 
-9
==========
7
-
-9
 = 
16
----------
16
+
-9
 = 
7
----------
-9
+
7
 = 
-2
----------
7
+
-2
 = 
5
----------
-2
+
5
 = 
3
----------
5
-
3
 = 
2
----------
3
-
2
 = 
1
----------
2
-
1
 = 
1
