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ASSASSIN  Assassin Creed 
Ezio needs to kill N targets located in N different cities. The cities are connected by some one way roads. As time is short, Ezio can send a massage along with the map to the assassin's bureau to send some assassins who will start visiting cities and killing the targets. An assassin can start from any city, he may visit any city multiple times even the cities that are already visited by other assassins. Now Ezio wants to find the minimum number of assassins needed to kill all the targets.
Input
Input starts with an integer T (≤ 70), denoting the number of test cases.
Each case starts with a blank line. Next line contains two integers N (1 ≤ N ≤ 1000) and M (0 ≤ M ≤ 10000), where N denotes the number of cities and M denotes the number of one way roads. Each of the next M lines contains two integers u v (1 ≤ u, v ≤ N, u ≠ v) meaning that there is a road from u to v. Assume that there can be at most one road from a city u to v.
Output
For each case, print the case number and the minimum number of assassins needed to kill all targets.
Sample Input 
Output for Sample Input 
3
5 4 1 2 1 3 4 1 5 1
7 0
8 8 1 2 2 3 3 4 4 1 1 6 6 7 7 8 8 6 
Case 1: 2 Case 2: 7 Case 3: 2 
Note
Dataset is huge, use faster I/O methods.
Được gửi lên bởi:  Race with time 
Ngày:  20121106 
Thời gian chạy:  1s2s 
Giới hạn mã nguồn:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Ngôn ngữ cho phép:  Tất cả ngoại trừ: ASM64 GOSU PERL6 PYPY RUST SED 
hide comments
20161224 20:59:56
SCC + Path Cover 

20160924 15:50:32
code: http://shink.in/wxiUV 

20150305 15:27:11 Duc M. Pham
Edited Last edit: 20150305 16:04:48 

20141126 15:33:20 livw
đề này của tàu khựa 

20121107 13:06:31 Race with time
Em bị TLE 

20121107 09:27:14 con_nha_ngheo
Ps xem hộ em xem em bị TLE hay là WA, em đc. 97.22 