../../../../comet2 a.o
+--------
12
++
12
+--------
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+-
+12
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++
1
+--------
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+-1
+-
1
+--------
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+32767
++
32767
+--------
+--------
+-32767
+-
32767
+--------
+--------
0
++
+0
+--------
+--------
+-32768
+OV
-32768
+--------