RT

#include <bits/stdc++.h>
using namespace std;
int n, m, value[100001], x, y, z, mn[100001], dp[100001];
vector <int> e[100001];
void dfs(int x, int nmin, int ans){
	dp[x] = max(dp[x], ans);
	mn[x] = min(mn[x], nmin);
	if (value[x] - nmin <= dp[x] && x != 1){
		return;
	}
	for (auto u : e[x]){
		dfs(u, min(nmin, value[x]), max(ans, value[x] - nmin));
	}
	return;
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= n; i++){
		cin >> value[i];
		mn[i] = 101;
	}
	for (int i = 1; i <= m; i++){
		cin >> x >> y >> z;
		e[x].push_back(y);
		if (z == 2){
			e[y].push_back(x);
		}
	}
	dfs(1, 101, 0);
	cout << dp[n];
	return 0;
}