Riga時間からDerry時間への変換
+7
+7
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+3
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+2
+2
+1.5
+1
+0.5
+0
+0
+0
+0
+0
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+0
-1
-1
-1
-1
-2
-2
-2
-2
-2
-2
-3
-6
-6
-6
-7
-7
-7
-8
-8
-9
-10