#include <bits/stdc++.h>
using namespace std;

const int N = 1.1e5;
int n, m, a[N], deg[N];
int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> a[i];
    while (m--) {
        int x, y;
        cin >> x >> y;
        deg[x]++, deg[y]++;
    }
    int ans{};
    if (n == 1) ans = a[1];
    for (int i = 1; i <= n; i++) {
        if (deg[i] > 1) {
            ans = max(ans, a[i]);
        }
    }
    cout << ans << '\n';
}