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

#define all(x) x.begin(), x.end()

// clang-format off
inline int read()
{
    int x = 0, f = 1; char ch = getchar();
    while(!isdigit(ch)) {if(ch == '-') f = -f; ch = getchar();}
    while(isdigit(ch)) {x = x * 10 + ch - '0'; ch = getchar();}
    return x * f;
}
// clang-format on

const int N = 100005;
vector<int> edges[N];
int w[N];

int main()
{
    int n = read(), m = read();
    for (int i = 1; i <= n; i++)
        w[i] = read();
    for (int i = 1; i <= m; i++)
    {
        int u = read(), v = read();
        edges[u].push_back(v);
        edges[v].push_back(u);
    }

    vector<int> leaves, other;
    for (int i = 1; i <= n; i++)
    {
        if (edges[i].size() == 1)
            leaves.push_back(w[i]);
        else
            other.push_back(w[i]);
    }
    sort(all(leaves), greater<int>());
    sort(all(other), greater<int>());

    if (leaves.size() <= 1)
    {
        if (!other.empty())
            cout << other[0];
        else
            cout << leaves[0]; // 当没有非叶子节点时，输出唯一的叶子节点
    }
    else
        cout << leaves[1];

    return 0;
}