#include "bits/stdc++.h"
#define int long long
using namespace std;
#define PII pair<int, int>
const int N = 2e6 + 10, M = 2e6 + 10, mod = 998244353, inf = 1e18;
double eps = 1e-9;
int n, m;
void solve()
{
    cin >> n >> m;
    vector<PII> a(n + 1);
    vector<PII> Max(n + 1);
    for (int i = 1; i <= n; i++)
        cin >> a[i].first, a[i].second = i;
    if (n == 1)
    {
        cout << a[1].first << endl;
        return;
    }
    vector<vector<int>> adj(n + 1);
    auto work = [&](int u, int val, int v)
    {
        if (val > Max[u].first)
            Max[u].second = Max[u].first, Max[u].first = val;
        else if (val > Max[u].second)
            Max[u].second = val;
    };
    for (int i = 1; i <= m; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].emplace_back(v), adj[v].emplace_back(u);
        work(u, a[v].first, v), work(v, a[u].first, v);
    }
    sort(a.begin() + 1, a.end(), greater<PII>());
    auto check = [&](int v, int val)
    {
        if (adj[v].size() >= 2)
            return true;
        int u = adj[v][0];
        // cout << u << endl;
        if (val == Max[u].first)
            return Max[u].second >= val;
        return Max[u].first >= val;
    };
    if (check(a[1].second, a[1].first))
    {
        cout << a[1].second << endl;
    }
    else
        cout << a[2].second << endl;
    // for (int i = 1; i <= n; i++)
    // {
    //     if (check(a[i].second, a[i].first))
    //     {
    //         cout << a[i].first << endl;
    //         return;
    //     }
    // }
}
signed main()
{

    // freopen("in.txt", "r", stdin);
    // freopen("out.txt", "w", stdout);

    int T = 1;
    // cin >> T;
    while (T--)
        solve();
    // cout<<round(0.5);
    return 0;
}