Count Empty Lines in a Stream

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Read the entire ASCII byte stream to EOF. An empty line is a zero-byte line terminated by LF (newline). Count an LF at the beginning of the stream, or an LF immediately following another LF. Space-only and tab-only lines are not empty. An empty file counts as zero; EOF does not create an implicit extra line.

Input

An ASCII stream of 0..100000 bytes (0..127); spaces, tabs, CR and LF are allowed. A trailing LF is optional.

Output

Print the empty-line count followed by LF.

Subtasks

• Subtask 1 (20%): ASCII stream length 0..100 bytes.

• Subtask 2 (30%): ASCII stream length 0..2000 bytes.

• Subtask 3 (50%): ASCII stream length 0..100000 bytes.

Examples

Example 1

Input:

Output:

0

Explanation:

Count only an LF at stream start or immediately after another LF. Exact input: ""; exact output: "0\n".

Example 2

Input:

Output:

1

Explanation:

Count only an LF at stream start or immediately after another LF. Exact input: "\n"; exact output: "1\n".

Example 3

Input:

A

B

Output:

1

Explanation:

Count only an LF at stream start or immediately after another LF. Exact input: "A\n\nB\n"; exact output: "1\n".

Example 4

Input:

A

Output:

3

Explanation:

Count only an LF at stream start or immediately after another LF. Exact input: "\n\nA\n\n"; exact output: "3\n".

Note on displayed bytes: \n denotes an actual LF, \t an actual tab and \r an actual CR. The JSON-style Input renderings in explanations are diagnostic only, not extra input characters.