Pulse

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Points: 3

Time limit: 2.0s

Memory limit: 64M

Problem type

You are in charge of all of a certain country's radio broadcasts. At time 0, you send outgoing radio waves to $N$ $N$ ( $1 \le N \le 1\,000$ $1 \leq N \leq 1 000$ ) receivers, and whenever a wave meets a receiver, the receiver immediately sends the wave back to you. If the waves travel at the same speed, which incoming radio waves will arrive between time $S$ $S$ and time $T$ $T$ ( $1 \le S \le T \le 10\,000$ $1 \leq S \leq T \leq 10 000$ ), inclusive?

Input Specification

On one line, $N$ $N$ , $S$ $S$ and $T$ $T$ , separated by single spaces followed by $N$ $N$ separate lines, each representing the time a radio wave meets a receiver. The times will be positive integers no greater than $10\,000$ $10 000$ .

Output Specification

The number of radio waves that made it back between time $S$ $S$ and time $T$ $T$ .

Sample Input

Copy

Sample Output

Copy

Explanation

Only the first two radio waves make it back, at times of exactly 2 and 4.

Comments

1

BULLET999 commented on Aug. 29, 2024, 3:39 a.m. ← edit 2 →

The problem should mention round trip time imo...