A positive integer will be called reachable if it can result from an arithmetic expression obeying the following rules:

• Uses the digits $1$ through $9$, in that order and exactly once each.
• Any successive digits can be concatenated (for example, using the digits $2$, $3$ and $4$ we obtain the number $234$).
• Only the four usual binary arithmetic operations (addition, subtraction, multiplication and division) are allowed.
• Each operation can be used any number of times, or not at all.
• Unary minusA minus sign applied to a single operand (as opposed to a subtraction operator between two operands) is not allowed.
• Any number of (possibly nested) parentheses may be used to define the order of operations.

For example, $42$ is reachable, since $(1/23)\times ((4\times 5)-6)\times (78-9)=42$.

What is the sum of all positive reachable integers?