I. Counter
time limit per test
1 second
memory limit per test
1024 megabytes
input
standard input
output
standard output

There is a counter with two buttons. Pressing the "+" button will increase the value on the counter by $$$1$$$ and pressing the "c" button will set the value on the counter to $$$0$$$. The initial value on the counter is $$$0$$$.

Someone has performed $$$n$$$ operations on the counter. Each operation is to press one of the two buttons. There are $$$m$$$ known conditions where the $$$i$$$-th condition can be described as two integers $$$a_i$$$ and $$$b_i$$$, indicating that after the $$$a_i$$$-th operation the value on the counter is $$$b_i$$$.

Is there a way to press the buttons so that all known conditions are satisfied?

Input

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

The first line contains two integers $$$n$$$ and $$$m$$$ ($$$1 \le n \le 10^9$$$, $$$1 \le m \le 10^5$$$) indicating the number of operations and the number of known conditions.

For the following $$$m$$$ lines, the $$$i$$$-th line contains two integers $$$a_i$$$ and $$$b_i$$$ ($$$1 \le a_i \le n$$$, $$$0 \le b_i \le 10^9$$$) indicating that after the $$$a_i$$$-th operation the value on the counter is $$$b_i$$$.

It's guaranteed that the sum of $$$m$$$ of all test cases will not exceed $$$5 \times 10^5$$$.

Output

For each test case output one line. If there exists a way to press the buttons so that all known conditions are satisfied, output Yes. Otherwise output No.

Example
Input
3
7 4
4 0
2 2
7 1
5 1
3 2
2 2
3 1
3 1
3 100
Output
Yes
No
No
Note

For the first sample test case, pressing buttons in the order of "++cc+c+" can satisfy all known conditions.

For the second sample test case, there are $$$8$$$ ways to press the buttons $$$3$$$ times.

Presses$$$2$$$-nd Op. Result$$$3$$$-rd Op. ResultPresses$$$2$$$-nd Op. Result$$$3$$$-rd Op. Result
ccc$$$0$$$$$$0$$$+cc$$$0$$$$$$0$$$
cc+$$$0$$$$$$1$$$+c+$$$0$$$$$$1$$$
c+c$$$1$$$$$$0$$$++c$$$2$$$$$$0$$$
c++$$$1$$$$$$2$$$+++$$$2$$$$$$3$$$

There is no way to satisfy all known conditions.

For the third sample test case, pressing the buttons $$$3$$$ times can only make the value on the counter at most $$$3$$$. It can't be $$$100$$$.