114. Telecasting station¶
time limit per test: 0.25 sec / memory limit per test: 4096 KB
Every city in Berland is situated on Ox axis. The government of the country decided to build new telecasting station. After many experiments Berland scientists came to a conclusion that in any city citizens displeasure is equal to product of citizens amount in it by distance between city and TV-station. Find such point on Ox axis for station so that sum of displeasures of all cities is minimal.
Input
Input begins from line with integer positive number N (0<N<15000) – amount of cities in Berland. Following N pairs (X, P) describes cities (0<X, P<50000), where X is a coordinate of city and P is an amount of citizens. All numbers separated by whitespace(s).
Output
Write the best position for TV-station with accuracy \(10^5\).
Example(s)
| Sample Input | Sample Output |
4
1 3
2 1
5 2
6 2
|
3.00000
|
| Author | Resource | Date |
|---|---|---|
| : Michael R. Mirzayanov | : PhTL #1 Training Contests | : Fall 2001 |