A traveller wants to drive from one city to another with minimum cost (assuming the gas tank is empty at the beginning). Given the distance between two cities is $D_1$, the capacity of the car's fuel tank is $C$ (in litres), the distance that a litre of gasoline can travel is $D_2$, the gas price per litre at the starting point is $P$, and there are $N$ gas stations along the way, the distance from the gas station $i$ to the starting point is $D_i$, and the price of gasoline per litre is $P_i$ ($i=1,2,\dots ,N$). Round your answer to two decimal places. If the destination cannot be reached, output No Solution.

Constraints

$1\le N\le 6$

$1\le D_1,C,D_2,P,P_i,D_i\le 500$

Input Specification

The first line contains five space-separated numbers, representing $D_1$, $C$, $D_2$, $P$ and $N$, respectively.

The next $N$ lines contain two numbers $D_i$, the distance from the starting point to the gas station $i$, and $P_i$, the price of gasoline per litre at the gas station $i$.

Output Specification

Output the minimum cost required, rounded to two decimal places. If the destination cannot be reached, output No Solution.

Sample Input

275.6 11.9 27.4 2.8 2
102.0 2.9
220.0 2.2

Sample Output

26.95

Problem translated to English by Tommy_Shan.