Welcome to ZOJ Problem Sets Information Select Problem Runs Ranklist ZOJ Problem Set - 3411
Special Special Judge

Time Limit: 2 Seconds      Memory Limit: 65536 KB

Because of recent update of ZOJ, some special judges were broken. You're requested to fix the special judge for Problem 0000.

The norm of a vector v = (v1, v2, ... , vn) is define as norm(v) = |v1| + |v2| + ... + |vn|. And in Problem 0000, there are n cases, the standard output is recorded as a vector x = (x1, x2, ... , xn). The output of a submitted solution is also records as a vector y = (y1, y2, ... , yn). The submitted solution will be accepted if and only if norm(x - y)m (a given tolerance).

Knowing that all the output xi are in range [a, b], an incorrent solution that outputs integer yi in range [a, b] with equal probability may also get accepted. Given the standard output xi, you are supposed to calculate the possibility of getting accepted using such solution.

#### Input

The input contains no more than 100 test cases. The first line of each case contains 4 integers n, m, a, b (1 ≤ n, m ≤ 50, -50 ≤ a < b ≤ 50), as described above. Then follows a line contains n integers, x1, x2, ... , xn (a ≤ xi ≤ b), indicating the standard output of the n cases.

Process to end of input.

#### Output

For each case, output the possibility as a irreducible fraction of getting accepted using the incorrent solution in a single line.

#### Sample Input

```1 1 0 2
1
```

#### Sample Output

```1/1
```

Author: LI, Dinghua
Contest: ZOJ Monthly, October 2010
Submit    Status