[USACO08JAN]haybale猜测Haybale Guessing


The cows, who always have an inferiority complex about their intelligence, have a new guessing game to sharpen their brains. A designated 'Hay Cow' hides behind the barn and creates N (1 ≤ N ≤ 1,000,000) uniquely-sized stacks (conveniently numbered 1..N) of hay bales, each with 1..1,000,000,000 bales of hay. The other cows then ask the Hay Cow a series of Q (1 ≤ Q ≤ 25,000) questions about the the stacks, all having the same form: What is the smallest number of bales of any stack in the range of stack numbers Ql..Qh (1 ≤ Ql ≤ N; Ql ≤ Qh ≤ N)?The Hay Cow answers each of these queries with a single integer A whose truthfulness is not guaranteed. Help the other cows determine if the answers given by the Hay Cow are self-consistent or if certain answers contradict others. 给一段长度为n,每个位置上的数都不同的序列a[1..n]和q和问答,每个问答是(x, y, r)代表RMQ(a, x, y) = r, 要你给出最早的有矛盾的那个问答的编号。(此处 RMQ 指最小值)



\* Line 1: Two space-separated integers: N and Q \* Lines 2..Q+1: Each line contains three space-separated integers that represent a single query and its reply: Ql, Qh, and A


\* Line 1: Print the single integer 0 if there are no inconsistencies among the replies (i.e., if there exists a valid realization of the hay stacks that agrees with all Q queries). Otherwise, print the index from 1..Q of the earliest query whose answer is inconsistent with the answers to the queries before it.


输入样例 #1

20 4
1 10 7
5 19 7
3 12 8
11 15 12

输出样例 #1