n,m=map(int,input().split())
S,G=map(int,input().split())
S-=1
G-=1
p=[tuple(map(int,input().split())) for i in range(n)]
e=[]
for i in range(m):
	s,g=map(int,input().split())
	s-=1
	g-=1
	sx,sy=p[s]
	gx,gy=p[g]
	d=((sx-gx)**2+(sy-gy)**2)**0.5
	e+=[(d,s,g)]
e.sort()

def root(x):
  p=x
  l=[p]
  while r[p]!=p:
    p=r[p]
    l+=[p]
  for p in l:
    r[p]=l[-1]
  return r[x]

def union(x,y):
  rx=root(x)
  ry=root(y)
  if rx==ry:
    return
  if rx>ry:
    rx,ry=ry,rx
  r[ry]=rx
  return

r=list(range(n))
C=0
for c,s,g in e:
	if root(s)!=root(g):
		union(s,g)
		C+=c
	if root(S)==root(G):
		break
print(C)