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)
    func = np.vectorize(lambda p, q: np.linalg.norm([np.array(_pq[p - 1]) - np.array(_pq[q - 1])]))
    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()