Conversion de l'heure de Siena à l'heure de Mexico City
18:51:52
-8
10:51:52
+7
+7
+7
+7
+7
+6
+6
+6
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+6
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+3.5
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+3.5
+3.5
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+3.5
+3.5
+3
+3
+2.5
+2
+1.5
+1
+1
+1
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+0
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-1
-1
-1
-1
-1
-2
-2
-5
-5
-5
-5
-6
-6
-7
-7
-8
-9