Pairing Chefs

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The Chef's latest idea is that some cooks might work better in pairs. So, he is going to experiment by pairing up some of his employees to see if the quality of the food prepared in his kitchen increases. However, only some pairs of employees are compatible. Two employees that are not compatible cannot be paired together.
For each pair of compatible employees, the Chef has assigned a number estimating how well the overall quality of the food might increase. Of course, each employee can only be paired with at most one other employee. Furthermore, it is ok to not pair some employees. So, your goal is to help the Chef decide how to pair the employees to maximize the total amount that the overall quality of food increases.
Input
The first line contains a single integer denoting the number of test cases (at most 50). Each test case begins with two integers n and m. Here, n is the number of employees (between 2 and 1000) and m is the number of compatible pairs of employees (between 1 and 10,000). The employees are numbered from 0 to n1. The next m lines describe a pair of compatible employees, one per line. The i'th such line contains two distinct integers u_{i},v_{i} between 0 and n1. Strangely enough, the Chef estimates that picking the i'th pair u_{i},v_{i} will increase the quality of food prepared in his kitchen by exactly 2^{i}.
No pair of employees will be given more than once in the input. That is, for distinct indices i and j, we do not have both u_{i} = u_{j} and v_{i} = v_{j}, nor do we have both u_{i} = v_{j} and v_{i} = u_{j}.
Output
The output for each test case consists of the indices of the pairs of employees that are used in a maximum total value pairing (the indices are between 0 and m1). These indices should be given in increasing order with a single space between consecutive numbers. If there is more than one possible output, then any will do.
Example
Input: 2 4 5 0 1 1 2 2 3 1 3 3 0 4 3 0 1 2 3 2 1 Output: 1 4 2
Author:  friggstad 
Tester:  rajivka 
Editorial  http://discuss.codechef.com/problems/PAIRING 
Tags  cook05, easy, friggstad 
Date Added:  4122010 
Time Limit:  2.28643 sec 
Source Limit:  50000 Bytes 
Languages:  C, CPP14, JAVA, PYTH, PYTH 3.6, CS2, PAS fpc, PAS gpc, RUBY, PHP, GO, NODEJS, HASK, SCALA, D, PERL, FORT, WSPC, ADA, CAML, ICK, BF, ASM, CLPS, PRLG, ICON, SCM qobi, PIKE, ST, NICE, LUA, BASH, NEM, LISP sbcl, LISP clisp, SCM guile, JS, ERL, TCL, PERL6, TEXT, PYP3, CLOJ, FS 
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