#include<bits/stdc++.h>

#define endl "\n"
// #define int long long

using namespace std;

using i64 = long long;
using u64 = unsigned long long;

constexpr int N = 5e5 + 10, M = 20;
constexpr int P = 1e9 + 7;
constexpr int INF = 1e9;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> du(n + 1, 0);
    vector<int> val(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> val[i];
    }
    while (m--) {
        int u, v;
        cin >> u >> v;
        du[u]++;
        du[v]++;
    }
    int mx = 0, mn = INF;
    
    for (int i = 1; i <= n; i++) {
        if (du[i] != 1) 
            mx = max(mx, val[i]);
        mn = min(mn, val[i]);
    }
    if (mn == INF) {
        mn = 0;
    }
    cout << max(mx, mn);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
}