Codeforces Round 142 (Div. 2)
E
Triangles
Codeforces
未评级
原题
← D→
翻译中…

Alice and Bob don't play games anymore. Now they study properties of all sorts of graphs together. Alice invented the following task: she takes a complete undirected graph with $*n*$ vertices, chooses some $*m*$ edges and keeps them. Bob gets the image remaining edges.

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Alice and Bob are fond of "triangles" in graphs, that is, cycles of length 3. That's why they wonder: what total number of triangles is there in the two graphs formed by Alice and Bob's edges, correspondingly?

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Input

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The first line contains two space-separated integers $*n*$ and $*m*$ ($1 ≤ *n* ≤ 10^{6}, 0 ≤ *m* ≤ 10^{6}$) — the number of vertices in the initial complete graph and the number of edges in Alice's graph, correspondingly. Then $*m*$ lines follow: the $*i*$-th line contains two space-separated integers $*a*_{*i*}$, $*b*_{*i*}$ ($1 ≤ *a*_{*i*}, *b*_{*i*} ≤ *n*$, $*a*_{*i*} ≠ *b*_{*i*}$), — the numbers of the two vertices connected by the $*i*$-th edge in Alice's graph. It is guaranteed that Alice's graph contains no multiple edges and self-loops. It is guaranteed that the initial complete graph also contains no multiple edges and self-loops.

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Consider the graph vertices to be indexed in some way from 1 to $*n*$.

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Output

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Print a single number — the total number of cycles of length 3 in Alice and Bob's graphs together.

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Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is advised to use the cin, cout streams or the %I64d specifier.

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Note

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In the first sample Alice has 2 triangles: (1, 2, 3) and (2, 3, 4). Bob's graph has only 1 triangle : (1, 4, 5). That's why the two graphs in total contain 3 triangles.

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In the second sample Alice's graph has only one triangle: (1, 2, 3). Bob's graph has three triangles: (1, 4, 5), (2, 4, 5) and (3, 4, 5). In this case the answer to the problem is 4.

翻译中…

样例

Input #1
5 5
1 2
1 3
2 3
2 4
3 4
Output #1
3
InputCopy OutputCopy
Input #2
5 3
1 2
2 3
1 3
Output #2
4
InputCopy OutputCopy
题目信息
题号
230E
时间限制
2 s
内存限制
256 MB

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