#include<bits/stdc++.h>
#define ll long long
const int N=100010;
using namespace std;
int n,m,a[N],fa[N],ans=-1;
struct Edge{int a,b,w;}e[N];
int father(int x) 
{
	if (fa[x]==x) return fa[x];
	fa[x]=father(fa[x]);
	return fa[x];
}
bool cmp(Edge x, Edge y){return x.w>y.w;}
int main()
{
	freopen("usaco_Jan_wormsort.in","r",stdin);
	freopen("usaco_Jan_wormsort.out","w",stdout);
	cin>>n>>m;
	for(int i=1;i<=n;i++)fa[i]=i,cin>>a[i];
	for(int i=1;i<=m;i++)cin>>e[i].a>>e[i].b>>e[i].w;
	sort(e+1,e+m+1,cmp);
	int ptr=1;
	for(int i=1;i<=m;i++)
	{
		while(father(ptr)==father(a[ptr])){ptr++;if(ptr>n)goto abcd;}
		int x=father(e[i].a);
		int y=father(e[i].b);
		if(x!=y)fa[x]=fa[y];
		ans=e[i].w;
	}
	abcd:;
	cout<<ans<<endl;
	return 0;
}