class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y


def lenv(a, b):
    return ((a.x - b.x) ** 2 + (a.y - b.y) ** 2) ** 0.5
n, l, k = map(int, input().split())
if k:
    holes = list(map(lambda x: int(x) - 1, input().split()))
else:
    holes = []
fence = []
for i in range(n):
    x, y = map(int, input().split())
    fence.append(Vector(x, y))
fromz = 0
pos = 0
l1 = 0
hl = [0]
ans = 0
for i in range(n):
    if i == holes[pos] and not pos:
        fromz = l1
        l1 = 0
        pos += 1
        pos %= k
    elif i == holes[pos]:
        hl.append(l1)
        l1 = 0
        pos += 1
        pos %= k
    else:
        l1 += lenv(fence[i], fence[(i + 1) % n])
    i += 1
    i %= n
hl[0] = l1 + fromz
s = 0
for hole_ind in range(k):
    s += lenv(fence[holes[hole_ind]], fence[(holes[hole_ind] + 1) % n])
    nowl = l
    ansn = 0
    ind = hole_ind
    flag = False
    while nowl > 0 and not (flag and ind == hole_ind):
        pos = holes[ind]
        tmp = lenv(fence[pos], fence[(pos + 1) % n])
        if tmp <= nowl:
            ansn += tmp
            nowl -= tmp
        else:
            ansn += nowl
            nowl = 0
        nowl -= hl[ind]
        ind = (ind + 1) % k
    ans = max(ansn, ans)
print(s - ans)