- Triple sum

# Triple sum

# Triple sum

Given arrays of different sizes, find the number of *distinct* triplets where is an element of , written as , , and , satisfying the criteria: .

For example, given and , we find four distinct triplets: .

**Function Description**

Complete the *triplets* function in the editor below. It must return the number of distinct triplets that can be formed from the given arrays.

triplets has the following parameter(s):

*a, b, c*: three arrays of integers .

**Input Format**

The first line contains integers , the sizes of the three arrays.

The next lines contain space-separated integers numbering respectively.

**Constraints**

**Output Format**

Print an integer representing the number of distinct triplets.

**Sample Input 0**

```
3 2 3
1 3 5
2 3
1 2 3
```

**Sample Output 0**

```
8
```

**Explanation 0**

The special triplets are .

**Sample Input 1**

```
3 3 3
1 4 5
2 3 3
1 2 3
```

**Sample Output 1**

```
5
```

**Explanation 1**

The special triplets are

**Sample Input 2**

```
4 3 4
1 3 5 7
5 7 9
7 9 11 13
```

**Sample Output 2**

```
12
```

**Explanation 2**

The special triplets are .