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![Acwing 341. 最优贸易 (spfa 求路径上最大的权差 Acwing 341. 最优贸易 (spfa 求路径上最大的权差](/default/index/img?u=aHR0cHM6Ly93d3cuaWNvZGU5LmNvbS9pL2xsLz9pPTMxYzMzYTVhNTc1NzRmMTVhNWM5Y2RhYWY5MjZjOGIzLnBuZz8sdHlwZV9abUZ1WjNwb1pXNW5hR1ZwZEdrLHNoYWRvd18xMCx0ZXh0X2FIUjBjSE02THk5aWJHOW5MbU56Wkc0dWJtVjBMMDFwYm1Wc2IybHosc2l6ZV8xNixjb2xvcl9GRkZGRkYsdF83MA==)
![Acwing 341. 最优贸易 (spfa 求路径上最大的权差 Acwing 341. 最优贸易 (spfa 求路径上最大的权差](/default/index/img?u=aHR0cHM6Ly93d3cuaWNvZGU5LmNvbS9pL2xsLz9pPTE4YWIyOWJhYzNhODRlYzNiY2MxYjQ2ZTcyNDIyNjFkLnBuZz8sdHlwZV9abUZ1WjNwb1pXNW5hR1ZwZEdrLHNoYWRvd18xMCx0ZXh0X2FIUjBjSE02THk5aWJHOW5MbU56Wkc0dWJtVjBMMDFwYm1Wc2IybHosc2l6ZV8xNixjb2xvcl9GRkZGRkYsdF83MA==)
#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10,M=1e6+10;
int n,m,w[N],hs[M],hd[M],e[M],ne[M],idx;
int minn[N],maxn[N],vis[N];
void add(int h[],int a,int b){
e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void spfa(int dist[],int flag,int h[]){
queue<int>q;
memset(vis,0,sizeof vis);
if(flag==1){
memset(dist,0x3f,sizeof minn);
dist[1]=w[1];
q.push(1);
}
else {
memset(dist,-0x3f,sizeof maxn);
dist[n]=w[n];
q.push(n);
}
// }cout<<"//"<<endl;
while(q.size()){
int p=q.front();
q.pop();
vis[p]=false;
for(int i=h[p];i!=-1;i=ne[i]){
int j=e[i];
if((flag==1&&dist[j]>min(dist[p],w[j]))||(flag==2&&dist[j]<max(dist[p],w[j]))){
if(flag==1)dist[j]=min(dist[p],w[j]);
else dist[j]=max(dist[p],w[j]);
if(!vis[j]){
vis[j]=true;
q.push(j);
}
}
}
}
}
int main(){
scanf("%d%d",&n,&m);
memset(hs,-1,sizeof hs);
memset(hd,-1,sizeof hd);
for(int i=1;i<=n;i++)scanf("%d",&w[i]);
while(m--){
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
add(hs,a,b);add(hd,b,a);
if(c==2){
add(hs,b,a);
add(hd,a,b);
}
}
spfa(minn,1,hs);
spfa(maxn,2,hd);
int ans=0;
// cout<<" *"<<endl;
for(int i=1;i<=n;i++){
ans=max(ans,maxn[i]-minn[i]);
}
printf("%d\n",ans);
return 0;
}