#include<bits/stdc++.h>
#define int long long
#define ll long long
#define ull unsigned long long
#define db double
#define P point
#define Fr(i,a,b) for(int i=a;i<=b;i++)
#define Fr_(i,a) for(auto i:a)
#define pb push_back
#define fastio ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define pii pair<int,int> 
#define fir first
#define sec second
#define pq priority_queue
#define mkp make_pair
#define memset(a,b) memset(a,b,sizeof(a))
#define new_opt friend bool operator
#define endl '\n'
#define ok cout<<"ok"<<endl

using namespace std;

const int N=2e6+10;
const int N_=1e3+10;
const int M=998244353;
const int inf=2e9;

int n,m;
struct node
{
    int v,du;
}t[N];

bool cmp(node x,node y)
{
    return x.v>y.v;
}

void slv()
{
    cin>>n>>m;
    Fr(i,1,n)
    {
        cin>>t[i].v;
    }
    Fr(i,1,m)
    {
        int x,y;
        cin>>x>>y;
        t[x].du++;
        t[y].du++;
    }
    vector<node> v1,v2;
    Fr(i,1,n)
    {
        if(t[i].du<=1) v1.pb(t[i]);
        else v2.pb(t[i]);
    }
    sort(v1.begin(),v1.end(),cmp);
    sort(v1.begin(),v1.end(),cmp);
    int ans=0;
    if(v1.size()>=2&&v2.size()>=1)
    {
        ans=max(v1[1].v,v2[0].v);
    }
    else if(v1.size()<2&&v2.size()>=1)
    {
        ans=v2[0].v;
    }
    else if(v1.size()>=2&&v2.size()==0)
    {
        ans=v1[1].v;
    }
    else if(v1.size()<2&&v2.size()==0){
        ans=v1[0].v;
    }

    else ans=v1[0].v;
    cout<<ans;
}
/*
6 5
1 2 3 4 5 1
1 2
1 3 
1 4
1 5
1 6

7 7
2 1 1 2 3 1 2 1
1 2
2 3
1 3
2 4
2 5
5 6
5 7
 
1 0
1
 */

signed main()
{
    //fastio;
    int o=1;
    //cin>>o;
    while(o--) slv();
}