#D4955. Deleting Numbers
Deleting Numbers
Deleting Numbers
This is an interactive problem.
There is an unknown integer x (1≤ x≤ n). You want to find x.
At first, you have a set of integers {1, 2, …, n}. You can perform the following operations no more than 10000 times:
- A a: find how many numbers are multiples of a in the current set.
- B a: find how many numbers are multiples of a in this set, and then delete all multiples of a, but x will never be deleted (even if it is a multiple of a). In this operation, a must be greater than 1.
- C a: it means that you know that x=a. This operation can be only performed once.
Remember that in the operation of type B a>1 must hold.
Write a program, that will find the value of x.
Input
The first line contains one integer n (1≤ n≤ 10^5). The remaining parts of the input will be given throughout the interaction process.
Interaction
In each round, your program needs to print a line containing one uppercase letter A, B or C and an integer a (1≤ a≤ n for operations A and C, 2≤ a≤ n for operation B). This line desribes operation you make.
If your operation has type C your program should terminate immediately.
Else your program should read one line containing a single integer, which is the answer to your operation.
After outputting each line, don't forget to flush the output. To do it use:
- fflush(stdout) in C/C++;
- System.out.flush() in Java;
- sys.stdout.flush() in Python;
- flush(output) in Pascal;
- See the documentation for other languages.
It is guaranteed, that the number x is fixed and won't change during the interaction process.
Hacks:
To make a hack, use such input format:
The only line should contain two integers n, x (1 ≤ x ≤ n ≤ 10^5).
Example
Input
10
2
4
0
Output
B 4
A 2
A 8
C 4
Note
Note that to make the sample more clear, we added extra empty lines. You shouldn't print any extra empty lines during the interaction process.
In the first test n=10 and x=4.
Initially the set is: {1,2,3,4,5,6,7,8,9,10}.
In the first operation, you ask how many numbers are multiples of 4 and delete them. The answer is 2 because there are two numbers divisible by 4: {4,8}. 8 will be deleted but 4 won't, because the number x will never be deleted. Now the set is {1,2,3,4,5,6,7,9,10}.
In the second operation, you ask how many numbers are multiples of 2. The answer is 4 because there are four numbers divisible by 2: {2,4,6,10}.
In the third operation, you ask how many numbers are multiples of 8. The answer is 0 because there isn't any number divisible by 8 in the current set.
In the fourth operation, you know that x=4, which is the right answer.
inputFormat
Input
The first line contains one integer n (1≤ n≤ 10^5). The remaining parts of the input will be given throughout the interaction process.
Interaction
In each round, your program needs to print a line containing one uppercase letter A, B or C and an integer a (1≤ a≤ n for operations A and C, 2≤ a≤ n for operation B). This line desribes operation you make.
If your operation has type C your program should terminate immediately.
Else your program should read one line containing a single integer, which is the answer to your operation.
After
outputFormat
outputting each line, don't forget to flush the output. To do it use:
- fflush(stdout) in C/C++;
- System.out.flush() in Java;
- sys.stdout.flush() in Python;
- flush(output) in Pascal;
- See the documentation for other languages.
It is guaranteed, that the number x is fixed and won't change during the interaction process.
Hacks:
To make a hack, use such input format:
The only line should contain two integers n, x (1 ≤ x ≤ n ≤ 10^5).
Example
Input
10
2
4
0
Output
B 4
A 2
A 8
C 4
Note
Note that to make the sample more clear, we added extra empty lines. You shouldn't print any extra empty lines during the interaction process.
In the first test n=10 and x=4.
Initially the set is: {1,2,3,4,5,6,7,8,9,10}.
In the first operation, you ask how many numbers are multiples of 4 and delete them. The answer is 2 because there are two numbers divisible by 4: {4,8}. 8 will be deleted but 4 won't, because the number x will never be deleted. Now the set is {1,2,3,4,5,6,7,9,10}.
In the second operation, you ask how many numbers are multiples of 2. The answer is 4 because there are four numbers divisible by 2: {2,4,6,10}.
In the third operation, you ask how many numbers are multiples of 8. The answer is 0 because there isn't any number divisible by 8 in the current set.
In the fourth operation, you know that x=4, which is the right answer.
样例
10
2
4
0
B 2
A 2
A 4
B 3
A 3
A 9
C 18
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