#include <bits/stdc++.h> #define REP(i, n) for(int i = 0;i < n;i++) #define ll long long using namespace std; //typedef vector<unsigned int>vec; //typedef vector<ll>vec; //typedef vector<vec> mat; typedef pair<int, int> P; typedef pair<ll,ll> LP; const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1}; const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1}; const int INF = 1000000000; const ll LINF = 1000000000000000000;//1e18 //const ll MOD = 1000000007; const ll MOD = 998244353; const double PI = acos(-1.0); const double EPS = 1e-10; template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } //template<class T> inline void add(T &a, T b){a = ((a+b) % MOD + MOD) % MOD;}; template<class T> class Dijkstra { public: int N; T inf; vector<T> cost; vector<vector<pair<T, int>>> edge; Dijkstra(const int N, T inf) : N(N), inf(inf),cost(N), edge(N) { } void make_edge(int from, int to, T w) { edge[from].push_back({ w,to }); } void solve(int start) { for(int i = 0; i < N; ++i) cost[i] = inf; priority_queue<pair<T, int>, vector<pair<T, int>>, greater<pair<T, int>>> pq; cost[start] = 0; pq.push({ 0,start }); while (!pq.empty()) { T v = pq.top().first; int from = pq.top().second; pq.pop(); for (auto u : edge[from]) { T w = v + u.first; int to = u.second; if (w < cost[to]) { cost[to] = w; pq.push({ w,to }); } } } return; } }; void solve(){ int N, M, X, Y; cin >> N >> M >> X >> Y; --X, --Y; Dijkstra<double> dijk(N, LINF); vector<double> p(N), q(N); REP(i,N) cin >> p[i] >> q[i]; REP(i,M){ int P, Q; cin >> P >> Q; --P, --Q; double cost = hypot(abs(p[P] - p[Q]), abs(q[P] - q[Q])); dijk.make_edge(P, Q, cost); dijk.make_edge(Q, P, cost); } dijk.solve(X); printf("%.12lf\n", dijk.cost[Y]); } int main(){ cin.tie(0); ios::sync_with_stdio(false); solve(); // int T; cin >> T; REP(t,T) solve(); }