Update message

src/main/java/seedu/address/logic/Messages.java

@@ -29,7 +29,7 @@ public class Messages {
             + "Amount should be a number of up to 2 decimal places.\n"
             + "Amount should contain only digits (0-9), at most 1 decimal point (.), and at most 1 minus sign (-).\n"
             + "If decimal point is used, there should be at least 1 digit before the decimal point.\n"
-            + "If the minus sign is used, it should be the first character.";
+            + "If minus sign is used, it should be the first character.";
     public static final String MESSAGE_INVALID_DATE_FORMAT = "Incorrect date format or invalid date!\n"
             + "Date format: YYYY-MM-DD";
     public static final String MESSAGE_INVALID_MONTH_FORMAT = "Incorrect month format or invalid month!\n"