Time Limit: 3000 MS Memory Limit: 65536 K

## Description

Tailmon has just finished the homework of "addition and subtraction£¨the number less than 10^8£©", please help her check. The format is a+b=c or a-b=c (Hint: c can be "?" , which means Tailmon cannot calculate).
## Input

The input contains no more than 100 lines, "EOF" to end of file .
Each line contains a subject, and does not contain any blank characters.
Input all integer shall not contain leading 0.
## Output

Output only a line, contains the number that Tailmon got the right answer.
## Sample Input

1+2=3

3-1=5

6+7=?

99-0=99

## Sample Output

2
## Author

yjx