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.