"""
from math import gcd
from itertools import accumulate, combinations, permutations, product, count
from bisect import bisect, bisect_left
from collections import Counter, defaultdict, deque
from heapq import heappush, heappop
from functools import reduce
from operator import add, mul, sub, truediv, floordiv, mod
from sortedcontainers import SortedSet, SortedList, SortedDict

from decimal import *
getcontext().prec = 500

import string
ascii = string.ascii_lowercase
"""

import numpy as np
from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import dijkstra
import sys


def main():
    input = lambda: sys.stdin.readline()[:-1]
    N, M = map(int, input().split())
    X, Y = map(int, input().split())
    _pq = np.array(list(input().split() for _ in [0] * N), dtype=np.int64)
    _PQ = np.array(list(input().split() for _ in [0] * M), dtype=np.int64)

    pq = np.transpose(_pq)
    PQ = np.transpose(_PQ)
    func = np.vectorize(lambda a, b: ((pq[0][a - 1] - pq[0][b - 1]) ** 2 + (pq[1][a - 1] - pq[1][b - 1]) ** 2) ** 0.5)
    dist = func(PQ[0], PQ[1])
    csr = csr_matrix((dist, PQ), (N + 1, N + 1))
    ans = dijkstra(csr, indices=X, directed=False)
    print(ans[Y])


if not __debug__:
    f = open(sys.argv[1], "r")
    sys.stdin = f

# try:
#     sys.set_int_max_str_digits(100000)
# except AttributeError:
#     pass

main()