Visiting a Friend

1000ms

262144K

Description:

Pig is visiting a friend.

Pig's house is located at point 0, and his friend's house is located at point m on an axis.

Pig can use teleports to move along the axis.

To use a teleport, Pig should come to a certain point (where the teleport is located) and choose where to move: for each teleport there is the rightmost point it can move Pig to, this point is known as the limit of the teleport.

Formally, a teleport located at point x with limit y can move Pig from point x to any point within the segment [x; y], including the bounds.

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Determine if Pig can visit the friend using teleports only, or he should use his car.

Input:

The first line contains two integers n and m (1 ≤ n ≤ 100, 1 ≤ m ≤ 100) — the number of teleports and the location of the friend's house.

The next n lines contain information about teleports.

The i-th of these lines contains two integers a_i and b_i (0 ≤ a_i ≤ b_i ≤ m), where a_i is the location of the i-th teleport, and b_i is its limit.

It is guaranteed that a_i ≥ a_i - 1 for every i (2 ≤ i ≤ n).

Output:

Print "YES" if there is a path from Pig's house to his friend's house that uses only teleports, and "NO" otherwise.

You can print each letter in arbitrary case (upper or lower).

Sample Input:

Sample Output:

YES

Sample Input:

Sample Output:

NO

Note:

The first example is shown on the picture below:

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Pig can use the first teleport from his house (point 0) to reach point 2, then using the second teleport go from point 2 to point 3, then using the third teleport go from point 3 to point 5, where his friend lives.

The second example is shown on the picture below:

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You can see that there is no path from Pig's house to his friend's house that uses only teleports.

Informação

Provedor Codeforces

Código CF902A