Solve the Missing Number in an Equation

You are given an equation in one of the forms \(X+Y=Z\) or \(X-Y=Z\). Two of the three numbers are provided and one of them is replaced by a question mark (?). Note that the equation may contain extra spaces.

Your task is to find the missing number. For instance, if the equation is ? + 2 = 3, then the missing number is 1 because \(1 + 2 = 3\).

The rules are as follows:

• If the missing number is in the place of \(X\) and the equation is \(?+Y=Z\), then compute \(X = Z - Y\).
• If the missing number is in the place of \(Y\) and the equation is \(X+?=Z\), then compute \(Y = Z - X\).
• If the missing number is in the place of \(Z\) and the equation is \(X+Y=?\), then compute \(Z = X + Y\).
• If the missing number is in \(X\) for the equation \(?-Y=Z\), then compute \(X = Z + Y\).
• If the missing number is in \(Y\) for the equation \(X-?=Z\), then compute \(Y = X - Z\).
• If the missing number is in \(Z\) for the equation \(X-Y=?\), then compute \(Z = X - Y\).

inputFormat

The input consists of a single line containing the equation with potential extra spaces. The numbers are integers, and one of the three numbers is replaced by a question mark (?).

outputFormat

Output the integer value of the missing number.

sample

? + 2 = 3

1