#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e6 + 10;
int a[N];
int de[N];
void solve()
{
    int n, m;
    cin >> n >> m;
    int maxi = -1e18;
    priority_queue<int> q;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    for (int i = 0; i < m; i++)
    {
        int u, v;
        cin >> u >> v;
        de[u]++;
        de[v]++;
    }
    if (n == 1)
    {
        cout << a[1] << endl;
        return;
    }
    for (int i = 1; i <= n; i++)
    {
        if (de[i] == 1)
        {
            q.push(-a[i]);
            if (q.size() > 2)
                q.pop();
        }
        else
        {
            maxi = max(maxi, a[i]);
        }
    }
    if (q.size())
    {
        maxi = max(maxi, -q.top());
        q.pop();
        maxi = max(maxi, -q.top());
    }
    cout << maxi << "\n";
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
}