Contest Duration: - (local time) (120 minutes) Back to Home
A - Ball Distribution /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 問題文

それぞれの人がボールを 1 個以上受け取るような配り方の中で、ボールが最も多い人と最も少ない人のボールの個数の差が最大で何個になるか求めてください。

### 制約

• 1 \leq K \leq N \leq 100
• 入力は全て整数である

### 入力

N K


### 出力

ボールの個数の差としてあり得る最大値を出力せよ。

### 入力例 1

3 2


### 出力例 1

1


それぞれの人がボールを 1 個以上受け取るように 3 個のボールを 2 人に配る方法は、1 人に 1 個、もう 1 人に 2 個配る方法のみです。

よってボールの個数の差の最大値は 1 です。

### 入力例 2

3 1


### 出力例 2

0


3 個のボールを 1 人に渡すしかなく、この時ボールの個数の差は 0 です。

### 入力例 3

8 5


### 出力例 3

3


Score : 100 points

### Problem Statement

Takahashi is distributing N balls to K persons.

If each person has to receive at least one ball, what is the maximum possible difference in the number of balls received between the person with the most balls and the person with the fewest balls?

### Constraints

• 1 \leq K \leq N \leq 100
• All values in input are integers.

### Input

Input is given from Standard Input in the following format:

N K


### Output

Print the maximum possible difference in the number of balls received.

### Sample Input 1

3 2


### Sample Output 1

1


The only way to distribute three balls to two persons so that each of them receives at least one ball is to give one ball to one person and give two balls to the other person.

Thus, the maximum possible difference in the number of balls received is 1.

### Sample Input 2

3 1


### Sample Output 2

0


We have no choice but to give three balls to the only person, in which case the difference in the number of balls received is 0.

### Sample Input 3

8 5


### Sample Output 3

3


For example, if we give 1, 4, 1, 1, 1 balls to the five persons, the number of balls received between the person with the most balls and the person with the fewest balls would be 3, which is the maximum result.