#include<bits/stdc++.h>

#define ff first
#define ss second

#define typet typename T
#define typeu typename U
#define types typename... Ts
#define tempt template < typet >
#define tempu template < typeu >
#define temps template < types >
#define final constexpr const

tempt struct range {
	T b, e;
	range (T b, T e): b(b), e(e) {}
	T begin() const {return b;}
	T end() const {return e;}
};
tempt range<T> make_range(T b, T e) {return range <T> (b, e);}

tempt struct is_cont {
	static final bool value = false;
};
tempt struct is_cont<range<T>>{
	static final bool value = true;
};
temps struct is_cont<std::vector<Ts...>>{
	static final bool value = true;
};
temps struct is_cont<std::set<Ts...>>{
	static final bool value = true;
};
temps struct is_cont<std::map<Ts...>>{
	static final bool value = true;
};
template < typet, typeu > std::ostream &
operator << (std::ostream &os, const std::pair<T, U> &p) {
	return os << '<' << p.ff << ',' << p.ss << '>';
}
tempt std::enable_if_t<is_cont<T>::value, std::ostream> &
operator << (std::ostream &os, const T &c) {
	auto it = c.begin();
	if (it == c.end()) return os << "{}";
	for (os << '{' << *it; ++it != c.end(); os << ',' << *it);
	return os << '}';
}
void dbg() {std::cerr << std::endl;}
template < typet, types > void dbg(T arg, Ts... args) {
	std::cerr << ' ' << arg; dbg(args...);
}
#ifndef ONLINE_JUDGE
#define debug(arg...) do {std::cerr << "["#arg"] :"; dbg(arg);} while (false)
#else
#define debug(...) do {} while (false)
#endif

using i64 = long long;
using vi = std::vector<int>;
using vl = std::vector<i64>;
using pii = std::pair<int, int>;
using vp = std::vector<pii>;
using vvi = std::vector<vi>;

#define lowbit(x) ((x) & (-x))
#define all(x) x.begin(), x.end()
#define set_all(x, y) std::memset(x, y, sizeof(x))
#define set_n(x, y, n) std::memset(x, y, sizeof(decltype(*(x))) * (n))

tempt void Min(T &x, const T &y) {if (x > y) x = y;}
tempt void Max(T &x, const T &y) {if (x < y) x = y;}

final int mod = 998244353;
inline int add(int x, int y) { return x + y < mod ? x + y : x + y - mod; }
inline int sub(int x, int y) { return x < y ? mod + x - y : x - y; }
inline int mul(i64 x, int y) { return x * y % mod; }
inline void Add(int& x, int y) { x = add(x, y); }
inline void Sub(int& x, int y) { x = sub(x, y); }
inline void Mul(int& x, int y) { x = mul(x, y); }
int pow(int x, int y) {
	int z = 1;
	for (; y; y /= 2) {
		if (y & 1) Mul(z, x);
		Mul(x, x);
	}
	return z;
}

void solve(int cas) {
	int n, m;
	std::cin >> n >> m;
	vi A(n + 1);
	vvi G(n + 1);
	for (int i = 1; i <= n; i++) {
		std::cin >> A[i];
	}
	for (int i = 0; i < m; i++) {
		int u, v;
		std::cin >> u >> v;
		G[u].emplace_back(A[v]);
		G[v].emplace_back(A[u]);
	}
	int ans = A[1];
	for (int i = 1; i <= n; i++) {
		std::sort(all(G[i]), std::greater<int>());
		if (G[i].size() >= 2) {
			Max(ans, G[i][1]);
			Max(ans, A[i]);
		}
	}
	std::cout << ans << '\n';
}

signed main() {
	std::cin.tie(nullptr) -> sync_with_stdio(false);
	int T = 1;
	//std::cin >> T;
	for (int cas = 1; cas <= T; cas++) {
		solve(cas);
	}
	return 0;
}
/*
7 7
1 1 2 3 1 2 1
1 2
2 3
1 3
2 4
2 5
5 6
5 7

*/