Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

The problem statement has recently been changed. View the changes.

×
F. Dirty Arkady's Kitchen

time limit per test

6 secondsmemory limit per test

512 megabytesinput

standard inputoutput

standard outputArkady likes to walk around his kitchen. His labyrinthine kitchen consists of several important places connected with passages. Unfortunately it happens that these passages are flooded with milk so that it's impossible to pass through them. Namely, it's possible to pass through each passage in any direction only during some time interval.

The lengths of all passages are equal and Arkady makes through them in one second. For security reasons, Arkady can never stop, also, he can't change direction while going through a passage. In other words, if he starts walking in some passage, he should reach its end and immediately leave the end.

Today Arkady needs to quickly reach important place *n* from place 1. He plans to exit the place 1 at time moment 0 and reach the place *n* as early as he can. Please find the minimum time he should spend on his way.

Input

The first line contains two integers *n* and *m* (1 ≤ *n* ≤ 5·10^{5}, 0 ≤ *m* ≤ 5·10^{5}) — the number of important places and the number of passages, respectively.

After that, *m* lines follow, each of them describe one passage. Each line contains four integers *a*, *b*, *l* and *r* (1 ≤ *a*, *b* ≤ *n*, *a* ≠ *b*, 0 ≤ *l* < *r* ≤ 10^{9}) — the places the passage connects and the time segment during which it's possible to use this passage.

Output

Print one integer — minimum time Arkady should spend to reach the destination. If he can't reach the place *n*, print -1.

Examples

Input

5 6

1 2 0 1

2 5 2 3

2 5 0 1

1 3 0 1

3 4 1 2

4 5 2 3

Output

3

Input

2 1

1 2 1 100

Output

-1

Note

In the first example Arkady should go through important places 1 → 3 → 4 → 5.

In the second example Arkady can't start his walk because at time moment 0 it's impossible to use the only passage.

Codeforces (c) Copyright 2010-2021 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: May/13/2021 13:24:40 (i1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|