import std.stdio, std.conv, std.functional, std.string;
import std.algorithm, std.array, std.container, std.range, std.typecons;
import std.bigint, std.numeric, std.math, std.random;
import core.bitop;

string FMT_F = "%.10f";

static File _f;
void file_io(string fn) { _f = File(fn, "r"); }
static string[] s_rd;
T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; }
T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; }
T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; }
T[] RDA(T = long)(T fix = 0) { if (_f.isOpen)  return _RDA!T(_f, fix); else return _RDA!T(fix); }

size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;}
size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; }

void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); }
bool inside(T)(T x, T b, T e) { return x >= b && x < e; }
T lcm(T)(T x, T y) { return x * (y / gcd(x, y)); }

//long mod = 10^^9 + 7;
long mod = 998_244_353;
//long mod = 1_000_003;
void moda(T)(ref T x, T y) { x = (x + y) % mod; }
void mods(T)(ref T x, T y) { x = ((x + mod) - (y % mod)) % mod; }
void modm(T)(ref T x, T y) { x = (x * y) % mod; }
void modpow(T)(ref T x, T y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); }
void modd(T)(ref T x, T y) { x.modm(y.modpow(mod - 2)); }

void main()
{
	auto N = RD;
	auto M = RD;
	auto X = RD-1;
	auto Y = RD-1;
	auto p = new long[](N);
	auto q = new long[](N);
	foreach (i; 0..N)
	{
		p[i] = RD;
		q[i] = RD;
	}
	auto edges = new double[][][](N);
	foreach (i; 0..M)
	{
		auto P = RD-1;
		auto Q = RD-1;
		auto d = sqrt(cast(double)((p[P]-p[Q])^^2 + (q[P]-q[Q])^^2));
		edges[P] ~= [Q, d];
		edges[Q] ~= [P, d];
	}

	auto heap = BinaryHeap!(Array!(double[]), "a[1] > b[1]")();
	heap.insert([X, 0.0]);
	auto dist = new double[](N);
	dist[] = double.max;
	dist[X] = 0.0;
	while (!heap.empty)
	{
		auto nd = heap.front; heap.removeFront;
		auto from = cast(long)nd[0];
		auto d = nd[1];
		foreach (e; edges[from])
		{
			auto to = cast(long)e[0];
			if (d+e[1] < dist[to])
			{
				dist[to] = d+e[1];
				heap.insert([to, dist[to]]);
			}
		}
	}

	writefln(FMT_F, dist[Y]);
	stdout.flush;
	debug readln;
}