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13/09/2024 10:11:28

# Рабочее место участника

## Задачи

Ограничения: время – 1s/2s, память – 64MiB Ввод: input.txt или стандартный ввод Вывод: output.txt или стандартный вывод
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The National Supermarket Chain (NSC) likes to boast that it has the lowest price for mortadella in the country. In fact, if a customer manages to find cheaper mortadella in any other chain, the NSC will match the price for that customer.
Matej and Filip decided to accept that challenge. They will visit N different supermarket chains in order to find mortadella not only cheaper than the one in NSC, but the cheapest on the market. If they are successful, they will be able to buy the cheapest mortadella in an NSC branch close to their school.
NSC was hoping that no one would be able to find cheaper mortadella since all supermarket chains (including NSC) express mortadella prices in a convoluted way: X dollars for Y grams of mortadella. Write a program to, given mortadella prices in NSC as well as the remaining N chains, determine the price that Matej and Filip will have to pay for 1000 grams of mortadella in the NSC close to their school.
The first line of input contains two positive integers X_"NSC" (1\ ≤\ X_"NSC"\ ≤\ 100) and Y_"NSC" (1\ ≤\ Y_"NSC"\ ≤\ 1000), where X_"NSC" is the price of Y_"NSC" grams of mortadella in the NSC chain.
The second line of input contains the positive integer N (1\ ≤\ N\ ≤\ 100), the number of supermarket chains (excluding NSC). Each of the following N lines contains two positive integers X_i (1\ ≤\ X_i\ ≤\ 100) and Y_i (1\ ≤\ Y_i\ ≤\ 1000), i=1..N, where X_i is the price of Y_i grams of mortadella in the ith supermarket chain.
The first and only line of output must contain the requested real number (price). It is allowed to differ at most 0.01 from the exact solution.

Sample Input #1

5 100
3
4 100
3 100
7 100


Sample Output #1

30.00


Sample Input #2

13 6
5
56 679
35 120
99 999
56 73
37 532


Sample Output #2

69.55


Sample Input #3

100 5
3
99 8
65 14
78 10


Sample Output #3

4642.86

Source: COCI 2012/2013, contest #2