PROGRAMMING:Interface -- four calculators
*Use the interface as a parameter, write a calculator, can complete the addition, subtraction, multiplication and division operation.
1. Define an interface icompute with a method int computer (int n, int m).
2. Define the add class, implement the interface icompute, implement the computer method, and calculate the sum of M and n
3. Define the sub class, implement the interface icompute, implement the computer method, and calculate the N-M difference
4. Define the main class, input two integers a and B in it, use the computer method of add class and sub class to find the sum of the first number a and the second number B, output the sum, the difference between the first number a and the second number B, and output the difference.
###Input format:
Enter 2 integers in one line
###Output format:
Output the sum and difference of two numbers
###Input example:
Here is a set of inputs. For example:
```in
6 7
```
###Output example:
The corresponding output is given here. For example:
```out
thirteen
-1
```
answer：If there is no answer, please comment
1. Define an interface icompute with a method int computer (int n, int m).
2. Define the add class, implement the interface icompute, implement the computer method, and calculate the sum of M and n
3. Define the sub class, implement the interface icompute, implement the computer method, and calculate the N-M difference
4. Define the main class, input two integers a and B in it, use the computer method of add class and sub class to find the sum of the first number a and the second number B, output the sum, the difference between the first number a and the second number B, and output the difference.
###Input format:
Enter 2 integers in one line
###Output format:
Output the sum and difference of two numbers
###Input example:
Here is a set of inputs. For example:
```in
6 7
```
###Output example:
The corresponding output is given here. For example:
```out
thirteen
-1
```
answer：If there is no answer, please comment