#include <algorithm> #include <bitset> #include <cassert> #include <chrono> #include <climits> #include <cmath> #include <complex> #include <cstring> #include <deque> #include <functional> #include <iostream> #include <iomanip> #include <list> #include <map> #include <numeric> #include <queue> #include <random> #include <set> #include <stack> #include <unordered_map> #include <unordered_set> #include <vector> #include <cstdint> using namespace std; typedef long long ll; typedef vector<int> vi; typedef pair<int,int> pii; #define MP make_pair #define PB push_back #define inf 1000000007 #define rep(i,n) for(int i = 0; i < (int)(n); ++i) #define all(x) (x).begin(),(x).end() template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ std::fill( (T*)array, (T*)(array+N), val ); } 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; } typedef long double ld; template<typename T> class Dijkstra { public: struct edge{ int to; T cost; }; int V; vector<vector<edge> > G; vector<T> d; using pti = pair<T,int>; Dijkstra(int node_size) : V(node_size), G(V), d(V, numeric_limits<T>::max()){} //無向グラフの場合 void add_edge(int u,int v,T cost){ G[u].push_back((edge){v,cost}),G[v].push_back((edge){u,cost}); } void solve(int s){ priority_queue<pti,vector<pti>,greater<pti> > que; d[s] = 0; que.push(pti(0,s)); while(!que.empty()){ pti p = que.top(); que.pop(); int v = p.second; if(d[v] < p.first) continue; for(auto& w : G[v]){ if(d[w.to] > d[v] + w.cost){ d[w.to] = d[v] + w.cost; que.push(pti(d[w.to],w.to)); } } } } }; int main(){ int n,m,a,b; cin >> n >> m >> a >> b; a--;b--; vector<ld>x(n),y(n); rep(i,n){ cin >> x[i] >> y[i]; } Dijkstra<ld> dk(n); rep(i,m){ int s,t; cin >> s >> t; s--;t--; dk.add_edge(s,t,sqrt((x[s]-x[t])*(x[s]-x[t])+(y[s]-y[t])*(y[s]-y[t]))); } dk.solve(a); cout.precision(30); cout << dk.d[b] << endl; return 0; }