#include<bits/stdc++.h>
using namespace std;
#define in f
#define out cout


ifstream f ("dragoni.in");
ofstream g ("dragoni.out");

int p;
int n;
int m;
int Dmax[50010];
int A[50010];
int B[50010];
int D[50010];
int viz[50010];
int node;
int rez;
queue <int> q;
vector <int > stl[1000];



int main() {

    in >> p;
    in >> n;
    in >> m;
    for(int i = 1; i <= n; i++) {
        in >> Dmax[i];
    }
    for(int i = 1; i <= m; i++) {
        in >> A[i];
        in >> B[i];
        in >> D[i];
        stl[A[i]].push_back(B[i]);
        stl[B[i]].push_back(A[i]);
    }
    rez = Dmax[1];
    q.push(1);
    viz[1]++;
    while(q.empty() == false) {
        node = q.front();
        q.pop();
        for(int i = 0; i < stl[node].size(); i++) {
            if((viz[stl[node][i]] == 0) && (D[stl[node][i]] <= Dmax[node])) {
                viz[stl[node][i]]++;
                q.push(stl[node][i]);
            }
        }
    }
    for(int i = 1; i <= n; i++) {
        if(viz[i] == 1) {
            rez = max(rez,Dmax[i]);
        }
    }
    out << rez;
}