Islington時間からKolkata時間への変換
17:50:15
+5.5
23:20:15
+7
+7
+7
+6.5
+6
+6
+6
+6
+5.5
+5.5
+5.5
+5.5
+5.5
+5.5
+5.5
+5.5
+5.5
+5.5
+5
+5
+4.5
+4
+3.5
+3
+3
+3
+3
+3
+3
+3
+2
+2
+2
+2
+1
+1
+1
+1
+1
+1
+1
+0
+0
-3
-3
-3
-3
-4
-5
-5
-5
-6
-8