Find the Unknown in an Arithmetic Equation

You are given an arithmetic equation of one of the following forms:

\(a \times b = c\) , \(a \div b = c\) , \(a + b = c\) , or \(a - b = c\)

In the equation, one of the three numbers \(a\), \(b\), or \(c\) is replaced by a question mark ? to indicate it is unknown. Your task is to determine the value of the unknown quantity.

For example, if the input is ?+2=5, then the unknown value is 3 since \(3+2=5\).

inputFormat

The input consists of a single line containing the equation as a string. The equation is always in one of the following forms: a*b=c, a/b=c, a+b=c, or a-b=c, where one of the numbers is replaced by ?.

outputFormat

Output the value of the unknown number as an integer.

sample

?+2=5

3