#include <bits/stdc++.h>

using namespace std;
int n, m;
int x, y, z;
int a[100005];
int ans;
struct graph {
	int f[100005];
	int g[100005];
	int vs[100005];
	vector<int>E[100005];
	void edd(int x, int y) {
		E[x].push_back(y);
	}
	void D(int nw, int la) {
		if (vs[nw])return;
		vs[nw] = 1;
		for (int i = 0; i < E[nw].size(); i++) {
//			cout << E[nw][i] << "\n";
			D(E[nw][i], nw);
			f[la] = max(f[la], f[nw]);
			g[la] = min(g[la], g[nw]);
		}
		return ;
	}
}G;
int main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		G.f[i] = G.g[i] = a[i];
	}
	G.edd(0, 1);
	G.f[0] = -0x7fffffff;
	G.g[0] = 0x7fffffff;
	for (int i = 1; i <= m; i++) {
		cin >> x >> y >> z;
		if (--z) {
			G.edd(y, x);
		}
		G.edd(x, y);
	}
	
	G.D(1, 0);
	
	cout << G.f[0] - G.g[0] << '\n';
	return 0;
}
/*
  
 */