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Problem 1799 Neighbor Friend

Accept: 60    Submit: 128
Time Limit: 1000 mSec    Memory Limit : 32768 KB

Problem Description

Suppose we sort N persons in a line according to their heights,we are curious about the Neighbor Friend. A pair of Neighbor Friend is two person next to each other in the line,ignoring the order(ie (x,y) and (y,x)is the same). Now you are given M pieces of infomation,each with two integer a and b,discribing that person a is shorter than person b. Can you find how many different pairs of Neighbor Friend that could occur in some of the sorted line?

Input

Input contains multiple cases. Each test case starts with two integer N(2<=N<=200) ,M(0<=M<1000) ,indicating that there are N persons and M pieces of information.Follow by M lines,each line contains two integers a and b,represents that person a is shorter than person b.

Output

For each test case, output the different pairs of Neighbor Friend that could occur in some of the sorted line.

Sample Input

3 1 1 2 3 2 1 2 2 3

Sample Output

3 2

Hint

In sample 1,we know that person 1 is shorter than person 2, there may be three kind of sorted results: 3 1 2,1 3 2,1 2 3.(1,3),(1,2) and (2,3) could be found among them. In sample 2,we know that person 1 is shorter than person 2,and person 2 is shorter than person 3, so there is only one kind of sorted results:1 2 3.We can’t find (1,3),so the answer is 2.

Source

Multi-School Training Contest - FOJ Site #7

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