#include<bits/stdc++.h>
using namespace std;
void print(vector<int> nums)
{
for(int x:nums)
cout<<x<<" ";
cout<<endl;
}
static cal3(vector<int> nums)
{
sort(nums.begin(),nums.end());
return nums[1];
}
class meth
{
public:
int n;
vector<vector<int>> edges;
//vector<int> leaf;
vector<int> lock;
vector<int> mark;
vector<int> status;
vector<int> nums;
meth(int sz,vector<vector<int>> raw_edges,vector<int> o_nums):edges(sz),mark(sz,0),status(sz,0),lock(sz,0)
{
n=sz;
nums=o_nums;
for(auto arr:raw_edges)
{
edges[arr[0]].push_back(arr[1]);
edges[arr[1]].push_back(arr[0]);
++lock[arr[0]];
++lock[arr[1]];
}
}
int cal()
{
int maxv=0;
for(int i=0;i<n;++i)
{
if(lock[i]==1)
continue;
maxv=max(maxv,nums[i]);
}
return maxv;
}
};
void Lonelyper(){
int n,m;
cin>>n>>m;
vector<int> weight(n);
for(auto&x:weight)
cin>>x;
vector<vector<int>> raw_edges(m,vector<int>(2));
for(auto&arr:raw_edges)
{
cin>>arr[0]>>arr[1];
--arr[0];
--arr[1];
}
if(n==1)
{
cout<<weight[0]<<endl;
return;
}
meth *test=new meth(n,raw_edges,weight);
int ans=test->cal();
cout<<ans<<endl;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
//cin >> t;
while(t --) Lonelyper();
return 0;
}