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# Дистанционный практикум по программированию

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## 47. Несложная торговля

 Ограничение времени: 2 сек. Ограничение памяти: 65536 КБайт Баллы: 100
 Статистика Послать на проверку Задачу добавил debug

Frank is a professional stock trader for Advanced Commercial Markets Limited (ACM Ltd). He likes "easy trading" - using a straightforward strategy to decide when to buy stock and when to sell it.

Frank has a database of historical stock prices for each day. He uses two integer numbers m and n (1 <= m < n <= 100) as parameters of his trading strategy. Every day he computes two numbers: P(m) - an average stock price for the previous m days, and P(n) - an average stock price for the previous n days. P(m) > P(n) is an indicator of the upward trend (traders call it bullish trend), and P(m) < P(n) is an indicator of the downward trend (traders call it bearish trend). In practice the values for P(m) and P(n) are never equal.

When a trend reverses from bearish to bullish it is a signal for Frank to buy stock. When a trend reverses from bullish to bearish it is a signal to sell.

Frank has different values for m and n in mind and he wants to backtest them using historical prices. He takes a set of k (n < k <= 10000) historical prices pi (0 < pi < 100 for 1 <= i <= k). For each i (n <= i <= k) he computes Pi(m) and Pi(n) - an arithmetic average of pi-m+1 ... pi and pi-n+1 ... pi respectively. Backtesting generates trading signals according to the following rules.

• If Pi(m) > Pi(n) there is a bullish trend for day i and a "BUY ON DAY i" signal is generated if i = n or there was a bearish trend on day i - 1.

• If Pi(m) < Pi(n) there is a bearish tread for day i and a "SELL ON DAY i" signal is generated if i = n or there was a bullish trend on day i - 1.

Your task is to write a program that backtests a specified strategy for Frank - you shall print a signal for the first tested day (day n) followed by the signals in increasing day numbers.

### Исходные данные

The first line of the input file contains three integer numbers m, n, and k. It is followed by k lines with stock prices for days 1 to k. Each stock price pi is specified with two digits after decimal point. Prices in the input file are such that Pi(m) <> Pi(n) for all i (n <= i <= k).

### Результат

Write to the output file a list of signals - one signal on a line, as described in the problem statement.

### Пример

Исходные данныеРезультат
```3 5 17
8.45
9.10
9.40
10.15
10.40
11.08
11.52
12.12
12.51
12.15
11.90
11.25
11.73
10.77
10.80
10.01
9.14```
```BUY ON DAY 5
SELL ON DAY 12```

 Статистика Послать на проверку Обсуждение задачи Автор/источник:
 46. D - Проиндексируйте документ 47 48. F - Найдите границу 49. G - Стрелок 50. H - Пирамидальная сортировка
 время генерации 0.125 сек. © Copyright ВоГУ, АВТ, Носов Д.А., Андрианов И.А.