Distinct Values

Chiaki has an array of $n$ positive integers. You are told some facts about the array: for every two elements $a_i$ and $a_j$ in the subarray $a_{l..r}$ ($l \le i < j \le r$), $a_i \ne a_j$ holds.
Chiaki would like to find a lexicographically minimal array which meets the facts.

There are multiple test cases. The first line of input contains an integer $T$, indicating the number of test cases. For each test case:

The first line contains two integers $n$ and $m$ ($1 \le n, m \le 10^5$) -- the length of the array and the number of facts. Each of the next $m$ lines contains two integers $l_i$ and $r_i$ ($1 \le l_i \le r_i \le n$).

It is guaranteed that neither the sum of all $n$ nor the sum of all $m$ exceeds $10^6$.

For each test case, output $n$ integers denoting the lexicographically minimal array. Integers should be separated by a single space, and no extra spaces are allowed at the end of lines.

3
2 1
1 2
4 2
1 2
3 4
5 2
1 3
2 4

1 2
1 2 1 2
1 2 3 1 1

2018 Multi-University Training Contest 1