#include<bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
using namespace std;
const int maxn=100001;
const int INF=0x7ffffff;
//暴力搜索20分。 
struct edge{
	int to,earn;
};
vector<edge>G[maxn];
int d[maxn],a[maxn];
int n,m;
void search(int cur){
	int earn=-INF;
	int l=G[cur].size();
	for(int i=0;i<l;i++){
		edge e=G[cur][0];
		//cout<<cur<<" "<<e.to<<" "<<e.earn<<endl;
		G[cur].erase(G[cur].begin());
		search(e.to);
		G[cur].push_back(e);
		int t=max(d[e.to],d[e.to]+e.earn);
		earn=max(earn,t);
	}
	d[cur]=max(d[cur],earn);
	//cout<<cur<<" "<<d[cur]<<endl; 
	return ;
}
int main(){
	freopen("trade.in","r",stdin);
	freopen("trade.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	for(int i=1;i<=m;i++){
		int x,y,z;
		scanf("%d%d%d",&x,&y,&z);
		edge t;t.to=y;t.earn=a[y]-a[x];
		G[x].push_back(t);
		if(z==2){
			t.to=x;t.earn=a[x]-a[y];
			G[y].push_back(t);
		}
	}
	fill(d+1,d+n+1,-INF);
	d[n]=0;
	//cout<<endl;
	search(1);
	printf("%d\n",d[1]);
	return 0;
}