from math import sqrt

#input
housepos = []
with open(raw_input("File\n-> ")[:-1]) as file:

	housepos.append(map(int, next(file).split(" ")))
	for i in range(19):
		house = next(file).split(" ")
		house[0] = int(house[0])
		house[1] = int(house[1])
 		housepos.append(house)

	housedist = []

	houseX = [k[0] for k in housepos]
	houseY = [k[1] for k in housepos]
	houseP = [k[2][0] for k in housepos[1:]]

	def dist(x1, y1, x2, y2):
		return sqrt(((x1 + x2)/2)**2 + ((y1 + y2)/2)**2)

	for n in range(len(housepos)-1):
		housedist.append([dist(houseX[0], houseY[0], houseX[n], houseY[n]), houseP[n]])

	housedist = sorted(housedist)

	deciders = [housedist[0], housedist[1], housedist[2]]

	#If dist = housedist[2] for any others (disregard pol standing) add it
	for x in range(len(housedist) -1):
		if x != 2:
			if housedist[x] == housedist[2]:
				deciders.append(housedist[x])

	houseP = [k[1] for k in housedist]
	pol = []
	for standing in houseP:
		if standing == "D":
			pol.append(1)
		else:
			pol.append(0)

	total = sum(pol)

	average = (float(total)/float(len(pol)) * 100.0)
	print average