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C - Super Ryuma /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 問題文

この駒は、 1 手で次のような動きができます。

より正確には、超竜馬がマス (a, b) にあるとき、以下のいずれかの条件を満たすマス (c, d) に動かすことができます。

• a + b = c + d
• a - b = c - d
• |a - c| + |b - d| \le 3

### 制約

• 入力は全て整数
• 1 \le r_1, c_1, r_2, c_2 \le 10^9

### 入力

r_1 c_1
r_2 c_2


### 入力例 1

1 1
5 6


### 出力例 1

2


### 入力例 2

1 1
1 200001


### 出力例 2

2


### 入力例 3

2 3
998244353 998244853


### 出力例 3

3


### 入力例 4

1 1
1 1


### 出力例 4

0


Score : 300 points

### Problem Statement

There is an infinite two-dimensional grid, and we have a piece called Super Ryuma at square (r_1, c_1). (Ryu means dragon and Ma means horse.) In one move, the piece can go to one of the squares shown below:

More formally, when Super Ryuma is at square (a, b), it can go to square (c, d) such that at least one of the following holds:

• a + b = c + d
• a - b = c - d
• |a - c| + |b - d| \le 3

Find the minimum number of moves needed for the piece to reach (r_2, c_2) from (r_1, c_1).

### Constraints

• All values in input are integers.
• 1 \le r_1, c_1, r_2, c_2 \le 10^9

### Input

Input is given from Standard Input in the following format:

r_1 c_1
r_2 c_2


### Output

Print the minimum number of moves needed for Super Ryuma to reach (r_2, c_2) from (r_1, c_1).

### Sample Input 1

1 1
5 6


### Sample Output 1

2


We need two moves - for example, (1, 1) \rightarrow (5, 5) \rightarrow (5, 6).

### Sample Input 2

1 1
1 200001


### Sample Output 2

2


We need two moves - for example, (1, 1) \rightarrow (100001, 100001) \rightarrow (1, 200001).

### Sample Input 3

2 3
998244353 998244853


### Sample Output 3

3


We need three moves - for example, (2, 3) \rightarrow (3, 3) \rightarrow (-247, 253) \rightarrow (998244353, 998244853).

### Sample Input 4

1 1
1 1


### Sample Output 4

0