Figures Area

# 1. Read figure type
import math

figure_type = input()

# 2. Check if:
#   a: square -> read "a" // calc
#   b: rectangle -> read width and length // calc
#   c: circle -> read radius
#   d: triangle -> read "a" and ha

a = float(input())
area = 0

if figure_type == "square":
    area = a * a
elif figure_type == "rectangle":
    b = float(input())
    area = a * b
elif figure_type == "circle":
    # pi * r * r
    area = math.pi * math.pow(a, 2)
elif figure_type == "triangle":
    height = float(input())
    area = a * height / 2

print("%.2f" % area)