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2050 . 尋找關節點 EXTREME
Description
給一張$N$點$M$邊的無向圖，保證連通、不含有自環、重邊。
請輸出滿足$a < b$且原圖移除$a, b$兩點後會不連通的點對$(a, b)$數量。
Input Format
第一行有兩個正整數$N, M(N\leq 2000, N - 1\leq M \leq \frac{N(N - 1)}{2})$，分別代表點數以及邊數。
接著$M$行每行有兩個正整數$u_i, v_i$，代表第$i$條邊連接$u_i$以及$v_i$。
| 子任務（測資） | 額外限制 | 分數 |
| 1 (0~31) | $N \leq 100$ | 21 |
| 2 (0~65) | $N \leq 800$ | 28 |
| 3 (0~99) | $N \leq 2000$ | 51 |
Output Format
輸出一個整數代表有幾對$(a, b)$滿足$a < b$且移除點$a$以及點$b$後會造成圖不連通。
Sample Input
Sample Input #1
6 7
1 2
1 3
2 3
3 4
4 5
5 6
4 6
Sample Input #2
4 4
1 2
2 3
3 4
1 4
6 7
1 2
1 3
2 3
3 4
4 5
5 6
4 6
Sample Input #2
4 4
1 2
2 3
3 4
1 4
Sample Output
Sample Output #1
9
Sample Output #2
2
9
Sample Output #2
2
Hints
範例測資一：移除$(1, 3)$、$(1, 4)$、$ (2, 3)$、$ (2, 4)$、 $(3, 4)$、 $(3, 5)$、$ (3, 6)$、$ (4, 5)$、 $(4, 6)$後皆會造成圖不連通。
範例測資二：移除$(1, 3)$、$(2, 4)$後皆會造成圖不連通。
Problem Source
Problem Set by WeaK, waynetuinfor
Subtasks
For Testdata: 0 ~ 31, Score: 21
For Testdata: 0 ~ 65, Score: 28
For Testdata: 0 ~ 99, Score: 51
For Testdata: 0 ~ 65, Score: 28
For Testdata: 0 ~ 99, Score: 51
| No. | Time Limit (ms) | Memory Limit (KiB) |
|---|---|---|
| 0 | 2000 | 262144 |
| 1 | 2000 | 262144 |
| 2 | 2000 | 262144 |
| 3 | 2000 | 262144 |
| 4 | 2000 | 262144 |
| 5 | 2000 | 262144 |
| 6 | 2000 | 262144 |
| 7 | 2000 | 262144 |
| 8 | 2000 | 262144 |
| 9 | 2000 | 262144 |
| 10 | 2000 | 262144 |
| 11 | 2000 | 262144 |
| 12 | 2000 | 262144 |
| 13 | 2000 | 262144 |
| 14 | 2000 | 262144 |
| 15 | 2000 | 262144 |
| 16 | 2000 | 262144 |
| 17 | 2000 | 262144 |
| 18 | 2000 | 262144 |
| 19 | 2000 | 262144 |
| 20 | 2000 | 262144 |
| 21 | 2000 | 262144 |
| 22 | 2000 | 262144 |
| 23 | 2000 | 262144 |
| 24 | 2000 | 262144 |
| 25 | 2000 | 262144 |
| 26 | 2000 | 262144 |
| 27 | 2000 | 262144 |
| 28 | 2000 | 262144 |
| 29 | 2000 | 262144 |
| 30 | 2000 | 262144 |
| 31 | 2000 | 262144 |
| 32 | 2000 | 262144 |
| 33 | 2000 | 262144 |
| 34 | 2000 | 262144 |
| 35 | 2000 | 262144 |
| 36 | 2000 | 262144 |
| 37 | 2000 | 262144 |
| 38 | 2000 | 262144 |
| 39 | 2000 | 262144 |
| 40 | 2000 | 262144 |
| 41 | 2000 | 262144 |
| 42 | 2000 | 262144 |
| 43 | 2000 | 262144 |
| 44 | 2000 | 262144 |
| 45 | 2000 | 262144 |
| 46 | 2000 | 262144 |
| 47 | 2000 | 262144 |
| 48 | 2000 | 262144 |
| 49 | 2000 | 262144 |
| 50 | 2000 | 262144 |
| 51 | 2000 | 262144 |
| 52 | 2000 | 262144 |
| 53 | 2000 | 262144 |
| 54 | 2000 | 262144 |
| 55 | 2000 | 262144 |
| 56 | 2000 | 262144 |
| 57 | 2000 | 262144 |
| 58 | 2000 | 262144 |
| 59 | 2000 | 262144 |
| 60 | 2000 | 262144 |
| 61 | 2000 | 262144 |
| 62 | 2000 | 262144 |
| 63 | 2000 | 262144 |
| 64 | 2000 | 262144 |
| 65 | 2000 | 262144 |
| 66 | 2000 | 262144 |
| 67 | 2000 | 262144 |
| 68 | 2000 | 262144 |
| 69 | 2000 | 262144 |
| 70 | 2000 | 262144 |
| 71 | 2000 | 262144 |
| 72 | 2000 | 262144 |
| 73 | 2000 | 262144 |
| 74 | 2000 | 262144 |
| 75 | 2000 | 262144 |
| 76 | 2000 | 262144 |
| 77 | 2000 | 262144 |
| 78 | 2000 | 262144 |
| 79 | 2000 | 262144 |
| 80 | 2000 | 262144 |
| 81 | 2000 | 262144 |
| 82 | 2000 | 262144 |
| 83 | 2000 | 262144 |
| 84 | 2000 | 262144 |
| 85 | 2000 | 262144 |
| 86 | 2000 | 262144 |
| 87 | 2000 | 262144 |
| 88 | 2000 | 262144 |
| 89 | 2000 | 262144 |
| 90 | 2000 | 262144 |
| 91 | 2000 | 262144 |
| 92 | 2000 | 262144 |
| 93 | 2000 | 262144 |
| 94 | 2000 | 262144 |
| 95 | 2000 | 262144 |
| 96 | 2000 | 262144 |
| 97 | 2000 | 262144 |
| 98 | 2000 | 262144 |
| 99 | 2000 | 262144 |