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## Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

## Goal

There are N apples on the tree. Every apple is a sphere with position (x, y, z) and radius r.
Then the i-th apple begins to fall straight down and can collide with others. When static apple gets hit by the falling one it begins to fall too, and the falling apple continues to fall straight down.
Your task is to determine how many apples will remain on the tree.

NOTE
"Down" direction is vector (0, 0, -1), i.e. apple with position (0,0,10) is higher than (0,0,5)
Input
Line 1 Two integers N and i – the number of apples and index of the falling apple
Next N lines Four space-separated integers X, Y, Z and R – position and radius of the apple
Output
A single integer – number of remaining apples
Constraints
1 ≤ N < 100
0 ≤ i < N
-1000000 ≤ x, y, z ≤ 1000000
1 ≤ r < 1000000
Example
Input
```2 0
0 0 100 10
0 0 200 15```
Output
`1`

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