18321번 - Wormhole Sort 다국어

문제

Farmer John's cows have grown tired of his daily request that they sort themselves before leaving the barn each morning. They have just completed their PhDs in quantum physics, and are ready to speed things up a bit.

This morning, as usual, Farmer John's $N$ cows (1ドル \leq N \leq 10^5$), conveniently numbered 1ドル \dots N,ドル are scattered throughout the barn at $N$ distinct locations, also numbered 1ドル \dots N,ドル such that cow $i$ is at location $p_i$. But this morning there are also $M$ wormholes (1ドル \leq M \leq 10^5$), numbered 1ドル \dots M,ドル where wormhole $i$ bidirectionally connects location $a_i$ with location $b_i,ドル and has a width $w_i$ (1ドル\le a_i,b_i\le N, a_i\neq b_i, 1\le w_i\le 10^9$).

At any point in time, two cows located at opposite ends of a wormhole may choose to simultaneously swap places through the wormhole. The cows must perform such swaps until cow $i$ is at location $i$ for 1ドル \leq i \leq N$.

The cows are not eager to get squished by the wormholes. Help them maximize the width of the least wide wormhole which they must use to sort themselves. It is guaranteed that it is possible for the cows to sort themselves.

입력

The first line contains two integers, $N$ and $M$.

The second line contains the $N$ integers $p_1, p_2, \dots, p_N$. It is guaranteed that $p$ is a permutation of 1ドル\ldots N.$

For each $i$ between 1ドル$ and $M,ドル line $i+2$ contains the integers $a_i,ドル $b_i,ドル and $w_i$.

출력

A single integer: the maximum minimal wormhole width which a cow must squish itself into during the sorting process. If the cows do not need any wormholes to sort themselves, output $-1$.

제한

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