题目描述
Let x1, x2, …, xm be real numbers satisfying the following conditions:
输入
Each input line contains four integers: m, p, a, b (m <= 2000, p <= 12, p is even).Input is correct, i.e. for each input numbers there exists x1, x2, …, xm satisfying the given conditions.
输出
For each input line print one number – the maximum value of expression, given above. The answer must be rounded to the nearest integer.
样例输入 Copy
1997 12 3 -318
10 2 4 -1
样例输出 Copy
189548
6