#include<bits/stdc++.h>
using namespace std;
#define int long long
#define ull long long
#define PII  pair<int ,int>
const int INF = 0x3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const int N = 1e6 + 5;
int fp(int a, int x, int mod) {
    int ans = 1;
    while (x) {
        if (x & 1)ans *= a;
        ans %= mod;
        a *= a;
        a %= mod;
        x >>= 1;
    }
    return ans;
}



//const int N = 1e6;
struct edge {
    int u, v;
};
struct node {
    int w;
    int id;
    bool operator<(const node& a)const {
        if (w != a.w)
            return w > a.w;
        else return id > a.id;
    }
};
int degree[N];
node a[N];
//vector<edge>e[N];
priority_queue<node>q;
priority_queue<node>e[N];
node st[N];
int top = 0;
int cnt = 0;
bool vis[N];

void solve() {
    int n, m;
    cin >> n >> m;
    int k = n;
    int cnt = n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i].w;
        vis[i] = 1;
        a[i].id = i;
        
    }
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
       /* e[u].push_back({ u,v });
        e[v].push_back({ v,u });*/
        e[u].push(a[v]);
        e[v].push(a[u]);
        degree[v]++;
        degree[u]++;
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (degree[i] >= 2)ans = max(a[i].w, ans);
    }
    cout <<ans<< endl;
}

signed main() {
   ios::sync_with_stdio(0);
   cin.tie(0), cout.tie(0);
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
}
/*
 7 7
  1 1 2 3 1 2 1
  1 2
  2 3
  1 3
  2 4
  2 5
  5 6
  5 7
*/