from scipy.spatial import distance
from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import dijkstra
from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    N, M = map(int, input().split())
    X, Y = map(int, input().split())
    pq = [tuple(map(int, input().split())) for _ in [0] * N]
    P, Q = zip(*[map(int, input().split()) for _ in [0] * M])

    dis = []
    for i, j in zip(P, Q):
        dis.append(distance.euclidean(pq[i-1], pq[j-1]))

    csr = csr_matrix((dis, (P, Q)), (N + 1, N + 1))
    ans = dijkstra(csr, directed=False)
    print(ans[X][Y])


main()