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Monk and the Islands
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Breadth-first search, Graph, Graph Theory

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Monk visits the land of Islands. There are a total of N islands numbered from 1 to N. Some pairs of islands are connected to each other by Bidirectional bridges running over water.
Monk hates to cross these bridges as they require a lot of efforts. He is standing at Island #1 and wants to reach the Island #N. Find the minimum the number of bridges that he shall have to cross, if he takes the optimal route.

Input:
First line contains T. T testcases follow.
First line of each test case contains two space-separated integers N, M.
Each of the next M lines contains two space-separated integers X and Y , denoting that there is a bridge between Island X and Island Y.

Output:
Print the answer to each test case in a new line.

Constraints:
1 ≤ T ≤ 10
1 ≤ N ≤ 104
1 ≤ M ≤ 105
1 ≤ X, YN

SAMPLE INPUT
2
3 2
1 2
2 3
4 4
1 2
2 3
3 4
4 2
SAMPLE OUTPUT
2
2
Time Limit: 3.0 sec(s) for each input file.
Memory Limit: 256 MB
Source Limit: 1024 KB

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