# Fish

Time Limit: 3000MS

Memory Limit: 131072KB

## Description

There're n fishes in a river holding a swimming match. The river just looks like x-axis, each fish has it's own start coordinate Xi, and heads towards the positive direction with the constant speed Vi. Between the match, transcendence will happen, it's specific definition is that: there're two fishes whose names are A and B, at a moment, A is ahead of B, but after a while, A is after B, that we call it transcendence. Now you need to calculate how many times does transcendence happen.

## Input

Multiple cases, end with EOF.

In each case, the first line is an integer n (1 < n < 10001), following with n lines, each line contains of two positive integers Xi, Vi (type of 32-bit signed integer), means the start point of each fish and its speed.

## Output

Print just one line for each case, means the times of transcendence.

## Sample Input

2

2 2

1 3

3

3 4

2 3

1 2


## Sample Output

1

0


None

None