An astronomy club has n stargazers, ranked 0 through n-1. Over a season, stargazers log constellation sightings; each log entry records which stargazer made it and which constellation type they saw. A stargazer earns a rank-up if there exists at least one constellation type for which the number of sightings that stargazer logged of that exact type is strictly greater than the stargazer's own rank number. (In particular, rank 0 earns a rank-up as soon as they log even a single sighting of any type, since any positive count is strictly greater than 0.) Count how many of the n stargazers earn a rank-up.

Input format

Line 1: two integers n m — the number of stargazers and the number of log entries. Each of the next m lines contains two integers s t — stargazer index s (0-indexed) logged one sighting of constellation type t.

Output format

A single integer: the number of stargazers who earn a rank-up.

Constraints

• 1 <= n <= 10
• 1 <= m <= 100
• 0 <= s <= n-1 for every log entry
• 0 <= t <= 10 for every log entry
• A stargazer with no log entries at all logs 0 sightings of every type and cannot earn a rank-up.

3 5
0 1
1 2
1 2
2 5
2 5

2

4 6
0 3
1 4
1 4
2 0
2 0
3 7

2