rt

#include <bits/stdc++.h>
#define ll long long
#define N 100010
#define M 210

using namespace std;
int n, m, add_edge; bool bian[M][M];
double px[M], py[M], dis[M]; 
int head[M * M * 2], from[M], vis[M];
struct CCC {
	int next, to; double dis;
}edge[M * M * 2];
struct node {
	int x; double dis;
	bool operator < (const node &b) const {
		return dis > b.dis;
	}
};

int read() {
	int s = 0, f = 0; char ch = getchar();
	while (!isdigit(ch)) f |= (ch == '-'), ch = getchar();
	while (isdigit(ch)) s = s * 10 + (ch ^ 48), ch = getchar();
	return f ? -s : s;
}

double distant(double x, double y, double a, double b) {
	return sqrt((x - a) * (x - a) + (y - b) * (y - b));
}

void add(int from, int to, double dis) {
	edge[++add_edge].next = head[from];
	edge[add_edge].to = to;
	edge[add_edge].dis = dis;
	head[from] = add_edge;
}

void dijkstra() {
	for (int i = 1; i <= n; i++) dis[i] = 444444444444.00;
	memset(vis, 0, sizeof vis);
	priority_queue<node> q;
	q.push((node){1, 0}), dis[1] = 0;
	while (!q.empty()) {
		node fr = q.top(); q.pop();
		int x = fr.x;
		if (vis[x]) continue;
		vis[x] = 1;
		for (int i = head[x]; i; i = edge[i].next) {
			int to = edge[i].to;
			if (bian[x][to]) continue;
			if (!vis[to] && dis[to] > dis[x] + edge[i].dis) {
				dis[to] = dis[x] + edge[i].dis; from[to] = x;
				q.push((node){to, dis[to]}); 
			}
		}
	} 
}

int main() {
	n = read(), m = read();
	for (int i = 1; i <= n; i++)
		px[i] = read(), py[i] = read();
	for (int i = 1, x, y; i <= m; i++) {
		x = read(), y = read();
		double d = distant(px[x], py[x], px[y], py[y]);
		add(x, y, d), add(y, x, d);
	}
	dijkstra();
	double an = dis[n];
	int sy = n; double ans = 444444444444.00;
	while (sy != 1) {
		bian[from[sy]][sy] = 1;
		dijkstra();
		if (dis[n] > an)
			ans = min(ans, dis[n]);
		bian[from[sy]][sy] = 0;
		sy = from[sy];
	}
	if (ans == 444444444444.00) puts("-1");
	else printf("%.2lf\n", ans);
}