#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define drep(i,j,n) for(int i=0;i<(int)(n-1);i++)for(int j=i+1;j<(int)(n);j++)
#define trep(i,j,k,n) for(int i=0;i<(int)(n-2);i++)for(int j=i+1;j<(int)(n-1);j++)for(int k=j+1;k<(int)(n);k++)
#define codefor int test;scanf("%d",&test);while(test--)
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define yes(ans) if(ans)printf("yes\n");else printf("no\n")
#define Yes(ans) if(ans)printf("Yes\n");else printf("No\n")
#define YES(ans) if(ans)printf("YES\n");else printf("NO\n")
#define popcount(v) __builtin_popcountll(v)
#define vector2d(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define vector3d(type,name,h,w,...) vector<vector<vector<type>>>name(h,vector<vector<type>>(w,vector<type>(__VA_ARGS__)))
#define vector4d(type,name,h,w,d,...) vector<vector<vector<vector<type>>>>name(h,vector<vector<vector<type>>>(w,vector<vector<type>>(d,vector<type>(__VA_ARGS__))))
using namespace std;
using ll = long long;
template<class T> using rpriority_queue = priority_queue<T, vector<T>, greater<T>>;
const int MOD=1000000007;
const int MOD2=998244353;
const int INF=1<<30;
const ll INF2=1LL<<60;
void scan(int& a){scanf("%d",&a);}
void scan(long long& a){scanf("%lld",&a);}
template<class T,class L>void scan(pair<T, L>& p){scan(p.first);scan(p.second);}
template<class T,class U,class V>void scan(tuple<T,U,V>& p){scan(get<0>(p));scan(get<1>(p));scan(get<2>(p));}
template<class T, size_t size> void scan(array<T, size>& a){ for(auto&& i : a) scan(i);}
template<class T> void scan(T& a){cin>>a;}
template<class T> void scan(vector<T>& vec){for(auto&& it:vec)scan(it);}
void in(){}
template <class Head, class... Tail> void in(Head& head, Tail&... tail){scan(head);in(tail...);}
void print(const int& a){printf("%d",a);}
void print(const long long& a){printf("%lld",a);}
void print(const double& a){printf("%.15lf",a);}
template<class T,class L>void print(const pair<T, L>& p){print(p.first);putchar(' ');print(p.second);}
template<class T> void print(const T& a){cout<<a;}
template<class T> void print(const vector<T>& vec){if(vec.empty())return;print(vec[0]);for(auto it=vec.begin();++it!= vec.end();){putchar(' ');print(*it);}}
void out(){putchar('\n');}
template<class T> void out(const T& t){print(t);putchar('\n');}
template <class Head, class... Tail> void out(const Head& head,const Tail&... tail){print(head);putchar(' ');out(tail...);}
template<class T> void dprint(const T& a){cerr<<a;}
template<class T> void dprint(const vector<T>& vec){if(vec.empty())return;cerr<<vec[0];for(auto it=vec.begin();++it!= vec.end();){cerr<<" "<<*it;}}
void debug(){cerr<<'\n';}
template<class T> void debug(const T& t){dprint(t);cerr<<endl;}
template <class Head, class... Tail> void debug(const Head& head, const Tail&... tail){dprint(head);cerr<<" ";debug(tail...);}
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
ll modinv(ll a, ll m) {ll b = m, u = 1, v = 0;while (b) {ll t = a / b;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;}
ll updivide(ll a,ll b){return (a+b-1)/b;}
template<class T> void chmax(T &a,const T b){if(b>a)a=b;}
template<class T> void chmin(T &a,const T b){if(b<a)a=b;}

template<class T> struct compressed_array{
    int N;
    vector<T> dat;
    const T operator[](int i) const { return dat[i]; }
    T operator[](int i) { return dat[i]; }
    compressed_array(){}
    compressed_array(vector<int> &a){
        dat=a;
    }
    void build(){
        sort(dat.begin(), dat.end());
        dat.erase(unique(dat.begin(), dat.end()), dat.end());
        N = dat.size();
    }
    int size(){return N;}
    void insert(const T v){
        dat.push_back(v);
    }
    void insert(vector<T> &a){
        for(int i = 0; i < a.size() ; i++)dat.push_back(a[i]);
    }
    //type1でfirst,type2でsecond
    void insert(vector<pair<T, T>> &a, int type){
        if(type==1){
            for(int i = 0; i < a.size(); i++)dat.push_back(a[i].first);
        }else{
            for(int i = 0; i < a.size(); i++)dat.push_back(a[i].second);
        }
    }
    template<size_t size> void insert(vector<array<T,size>> &a, int pos){
        assert(0 <= pos && pos < size);
        for(int i = 0; i < a.size() ; i++){
            dat.push_back(a[i][pos]);
        }
    }
    int load(T &v){
        return lower_bound(dat.begin(), dat.end(), v) - dat.begin();
    }
    void load(vector<T> &a){
        for(int i = 0; i < a.size() ; i++)a[i] = load(a[i]);
    }
    void load(vector<pair<T, T>> &a, int type){
        if(type==1){
            for(int i = 0; i < a.size(); i++)a[i].first = load(a[i].first);
        }else{
            for(int i = 0; i < a.size(); i++)a[i].second = load(a[i].second);
        }
    }
    template<size_t size> void load(vector<array<T,size>> &a, int pos){
        assert(0 <= pos && pos < size);
        for(int i = 0; i < a.size() ; i++){
            a[i][pos] = load(a[i][pos]);
        }
    }
};

//Union Add Query
struct dsu{
    using U = long long;
    int n;
    vector<pair<int,U>> dat;
    dsu() : n(0) {}
    dsu(int _n) : n(_n), dat(_n, {-1, 0}) {}
    int merge(int a, int b) {
        assert(0 <= a && a < n);
        assert(0 <= b && b < n);
        int x = leader(a).first, y = leader(b).first;
        if (x == y) return x;
        if (-dat[x].first < -dat[y].first) std::swap(x, y);
        dat[x].first += dat[y].first;
        dat[y].first = x;
        dat[y].second -= dat[x].second;
        return x;
    }
    pair<int,U> leader(int a) {
        assert(0 <= a && a < n);
        if (dat[a].first < 0 ) return {a, 0};
        auto p = leader(dat[a].first);
        dat[a].first = p.first;
        dat[a].second += p.second;
        return dat[a];
    }
    void add(int a, U v){
        assert(0 <= a && a < n);
        dat[leader(a).first].second += v;
    }
    U get(int a){
        assert(0 <= a && a < n);
        auto p = leader(a);
        return p.second + dat[p.first].second;
    }
};

int main(){
    INT(n,m,s,t);
    s--,t--;
    dsu uf(n);
    vector<int> p(n);
    in(p);
    compressed_array<int> ca(p);
    ca.build();
    ca.load(p);
    vector<vector<int>> tb(ca.size());
    for(int i=0;i<n;i++){
        tb[p[i]].push_back(i);
    }
    vector<vector<int>> g(n);
    int u,v;
    for(int i=0;i<m;i++){
        in(u,v);
        u--,v--;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    vector<bool> used(n);
    for(int i=ca.size()-1;i>=0;i--){
        set<int> S;
        for(auto &&v:tb[i]){
            for(auto &&u:g[v]){
                if(!used[u])continue;
                S.insert(uf.leader(u).first);
            }
        }
        for(auto &&v:S)uf.add(v,1);
        for(auto &&v:tb[i]){
            for(auto &&u:g[v]){
                if(!used[u])continue;
                uf.merge(u,v);
            }
            used[v]=true;
        }
    }
    out(uf.get(s));
}