#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

struct UnionFind {
public:
	using size_type = std::size_t;
	
	UnionFind(size_type n) : n(n), size_(n, 1) {
		par.resize(n);
		std::iota(par.begin(), par.end(), 0);
	}
	
	size_type size(size_type x) { return size_[find(x)]; }
	
	size_type find(size_type x) {
		assert(x < n);
		while (par[x] != x) {
			par[x] = par[par[x]];
			x = par[x];
		}
		return x;
	}
	
	void unite(size_type x, size_type y) {
		x = find(x);
		y = find(y);
		if (x == y) return;
		if (size(x) > size(y)) std::swap(x, y);
		par[x] = y;
		size_[y] += size_[x];
	}
	
	bool issame(size_type x, size_type y) { return find(x) == find(y); }
	
private:
	size_type n;
	std::vector<size_type> size_, par;
};

int main() {
	int N, M, S, T;
	cin >> N >> M >> S >> T; --S; --T;
	vector<int> P(N);
	REP(i, N) scanf("%d", &P[i]);
	vector<vector<int>> g(N);
	REP(i, M){
		int a, b;
		scanf("%d %d", &a, &b);
		--a; --b;
		g[a].emplace_back(b);
		g[b].emplace_back(a);
	}
	vector<int> ord(N);
	iota(ALL(ord), 0);
	sort(ALL(ord), [&](int i, int j) { return P[i] > P[j]; });
	int cur = P[S], ans = 0;
	UnionFind uf(N);
	for (int i : ord) {
		for (int v : g[i]) uf.unite(i, v);
		if (uf.issame(S, i) && chmin(cur, P[i])) ++ans;
	}
	cout << ans << endl;
}