Problem Statement
We have a $N$-face die (singular of dice) that shows integers from $1$ through $N$ with equal probability.
Below, the die is said to be showing an integer $X$ when it is placed so that the top face is the face with the integer $X$.
Initially, the die shows the integer $S$.
You can do the following two operations on this die any number (possibly zero) of times in any order.
- Pay
$A$yen (the Japanese currency) to "increase" the value shown by the die by$1$, that is, reposition it to show$X+1$when it currently shows$X$. This operation cannot be done when the die shows$N$. - Pay
$B$yen to recast the die, after which it will show an integer between$1$and$N$with equal probability.
Consider making the die show $T$ from the initial state where it shows $S$.
Print the minimum expected value of the cost required to do so when the optimal strategy is used to minimize this expected value.
Constraints
$1 \leq N \leq 10^9$$1 \leq S, T \leq N$$1 \leq A, B \leq 10^9$- All values in input are integers.
Input
Input is given from Standard Input in the following format:
N S T A B
Output
Print the answer. Your output will be considered correct when its absolute or relative error is at most $10^{-5}$.
样例
5 2 4 10 4
15.0000000000000000
10 6 6 1 2
0.0000000000000000
1000000000 1000000000 1 1000000000 1000000000
1000000000000000000.0000000000000000
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