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Given a string representing arbitrarily nested ternary expressions, calculate the result of the expression. You can always assume that the given expression is valid and only consists of digits `0-9`

, `?`

, `:`

, `T`

and `F`

(`T`

and `F`

represent True and False respectively).

**Note:**

- The length of the given string is ≤ 10000.
- Each number will contain only one digit.
- The conditional expressions group right-to-left (as usual in most languages).
- The condition will always be either
`T`

or`F`

. That is, the condition will never be a digit. - The result of the expression will always evaluate to either a digit
`0-9`

,`T`

or`F`

.

**Example 1:**

Input:"T?2:3"Output:"2"Explanation:If true, then result is 2; otherwise result is 3.

**Example 2:**

Input:"F?1:T?4:5"Output:"4"Explanation:The conditional expressions group right-to-left. Using parenthesis, it is read/evaluated as: "(F ? 1 : (T ? 4 : 5))" "(F ? 1 : (T ? 4 : 5))" -> "(F ? 1 : 4)" or -> "(T ? 4 : 5)" -> "4" -> "4"

**Example 3:**

Input:"T?T?F:5:3"Output:"F"Explanation:The conditional expressions group right-to-left. Using parenthesis, it is read/evaluated as: "(T ? (T ? F : 5) : 3)" "(T ? (T ? F : 5) : 3)" -> "(T ? F : 3)" or -> "(T ? F : 5)" -> "F" -> "F"

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