#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define ull unsigned long long
#define PII pair<int, int>
#define fi first
#define se second
#define inf 0x3f3f3f3f3f3f3f3f
const int N=2e5+10,mod=998244353,P=131;

void solve()
{
    int n , m;
    cin >> n >> m;
    vector<int> a(n + 1);
    vector<vector<int>> p(n + 1);
    for(int i = 1 ; i <= n ; i ++ ) cin >> a[i];
    int x , y;
    while(m -- ) {
        cin >> x >> y;
        p[x].push_back(y);
        p[y].push_back(x);
    }
    if(n == 1) {
        cout << a[1] << '\n';
        return;
    }
    int ans = 0;
    for(int i = 1 ; i <= n ; i ++ ) {
        if(p[i].size() == 1) continue;
        // cout << i << ':' << p[i].size() << ' ';
        int res = a[i];
        vector<int> pu;
        for(auto j : p[i]) pu.push_back(a[j]);
        sort(pu.begin() , pu.end());
        res = max(res , pu[pu.size() - 2]);
        ans = max(ans , res);
    }
    cout << ans << '\n';
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T=1;
    // cin>>T;
    while (T--)
        solve();
    return 0;
}