B. Road Intersections
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

In the search for Planet B, scientists found an alternate reality. When they entered it, the scientists found themselves in an alternate version of Manhattan.

There are $$$N$$$ roads in this version of Manhattan, either an avenue (going North to South) or a street (going East to West), much like the original. In short, avenues are vertical lines, and streets are horizontal lines. No one has reached the end of a road, so assume that they go on infinitely in both directions.

Each time an avenue and a street intersect, there is an intersection. Find the number of intersections in the new Manhattan, given their unchanging coordinate (that would be $$$x$$$ coordinate for avenues, and $$$y$$$ coordinate for streets).

Word to the wise: it is possible that there are either no avenues or no streets. Also, no road is repeated in input.

Input

Line $$$1$$$: $$$N$$$ ($$$1 \le N \le 10^3$$$), the total number of roads. They can be either avenues or streets.

Lines $$$2...N+1$$$: the letter $$$h$$$ or $$$v$$$, $$$h$$$ if the line is horizontal, and $$$v$$$ if the line is vertical. After that is the coordinate of the line $$$a_i$$$ ($$$-10^9 \le a_i \le 10^9$$$).

Output

Line 1: The number of intersections

Example
Input
5
h 3
h 2
h 1
v 2
v 1
Output
6
Note

No lines will be given twice in the input.