# include <bits/stdc++.h>
# define int long long
const int N(1e5 + 5);
int w[N], deg[N];
typedef struct Node
{
    int w, e, id;
}nd;
std::vector<nd> a;
std::vector<int> G[N];

int get_max(int u)
{
    int val = 1e9;
    for (auto v: G[u])
    {
        val = std::min(val, w[v]);
    }
    if (val == 1e9)
        val = 0;
    return std::max(w[u], val);
}

void solve()
{
    int n, m;
    std::cin >> n >> m;
    for (int i = 1; i <= n; ++i)
        std::cin >> w[i];
    for (int i = 1; i <= m; ++i)
    {
        int u, v;
        std::cin >> u >> v;
        G[u].push_back(v), G[v].push_back(u);
        deg[u]++, deg[v]++;
    }
    if (n == 1)
    {
        std::cout << w[1] << '\n';
        return;
    }
    for (int i = 1; i <= n; ++i)
        a.push_back({w[i], deg[i], i});
    std::sort(a.begin(), a.end(), [](nd x, nd y)
        {
            if (x.w != y.w)
                return x.w > y.w;
            if (x.e != y.e)
                return x.e > y.e;
            return x.id < y.id;
        });
    int tarw;
    for (auto t: a)
    {
        if (t.e > 1)
        {
            tarw = t.w;
            break;
        }
    }
    int ans = 0;
    for (auto t: a)
    {
        if (tarw == t.w)
        {
            ans = std::max(ans, get_max(t.id));
        }
    }
    std::cout << ans << '\n';
}

signed main(void)
{
    solve();
}