import sys

import numpy as np
from scipy.sparse import coo_matrix
from scipy.sparse.csgraph import dijkstra


def input():
    return sys.stdin.readline()[:-1]


def main():
    N, M = map(int, input().split())
    X, Y = map(int, input().split())
    pq = [np.array(list(map(int, input().split()))) for _ in [0] * N]
    P, Q = zip(*[map(int, input().split()) for _ in [0] * M])

    dis = np.array([np.linalg.norm(pq[j - 1] - pq[i - 1]) for i, j in zip(P, Q)])
    P, Q = np.array(P), np.array(Q)
    csr = coo_matrix((dis, (P, Q)), (N + 1, N + 1)).tocsr()
    ans = dijkstra(csr, indices=X, directed=False)
    print(ans[Y], flush=True)


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

main()