#include<bits/stdc++.h>
#define int long long
#define db double
#define pii pair<int, int>
#define ll long long
using namespace std;
const int N = 1e5 + 999;
int a[N], d[N], n, m;
void solve() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++){
        cin >> a[i];
    }
    for(int i = 1; i <= m; i++){
        int u, v;
        cin >> u >> v;
        d[u]++;
        d[v]++;
    }
    int ans = 0;
    for (int i = 1; i <= n; i++)
         if(d[i] > 1 || n == 1) ans = max(ans, a[i]);
    cout << ans << '\n';
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}