import math

f = []

while True:

    try:

        st = input().strip().split(',')

        x,y = list(map(float,st ))

        f.append(x + y*1j)

    except EOFError:

        break



px = [p.real for p in f]

ox = (max(px) + min(px)) / 2.0



py = [p.imag for p in f]

oy = (max(py) + min(py)) / 2.0



fo = ox + oy * 1j



ss = 0.0

for i in range(len(f)):

    if i == len(f)-1:

        j = 0

    else:

        j = i + 1

    a = abs(f[i]-fo)

    b = abs(f[j]-fo)

    c = abs(f[j]-f[i])

    z = (a + b + c) / 2.0

    s = math.sqrt(z*(z-a)*(z-b)*(z-c))

    ss += s

print(("%.6f" % ss))
def cross(x, y):

    return (x.conjugate() * y).imag

 

def area_polygon(points):

    area = 0

    n = len(points)

    for i in range(n):

        area += cross(points[i], points[(i+1)%n])

    return area / 2

     

     

import sys

 

p = []

for line in sys.stdin:

    x, y = list(map(float, line.split(',')))

    p.append(complex(x, y))

 

print((area_polygon(p)))
import math

f = []
while True:
    try:
        st = input().strip().split(",")
        x, y = list(map(float, st))
        f.append(x + y * 1j)
    except EOFError:
        break
px = [p.real for p in f]
ox = (max(px) + min(px)) / 2.0
py = [p.imag for p in f]
oy = (max(py) + min(py)) / 2.0
fo = ox + oy * 1j
ss = 0.0
for i in range(len(f)):
    if i == len(f) - 1:
        j = 0
    else:
        j = i + 1
    a = abs(f[i] - fo)
    b = abs(f[j] - fo)
    c = abs(f[j] - f[i])
    z = (a + b + c) / 2.0
    s = math.sqrt(z * (z - a) * (z - b) * (z - c))
    ss += s
print(("%.6f" % ss))

def cross(x, y):
    return (x.conjugate() * y).imag


def area_polygon(points):
    area = 0
    n = len(points)
    for i in range(n):
        area += cross(points[i], points[(i + 1) % n])
    return area / 2


import sys

p = []
for line in sys.stdin:
    x, y = list(map(float, line.split(",")))
    p.append(complex(x, y))
print((area_polygon(p)))

-import math +def cross(x, y): +    return (x.conjugate() * y).imag -f = [] -while True: -    try: -        st = input().strip().split(",") -        x, y = list(map(float, st)) -        f.append(x + y * 1j) -    except EOFError: -        break -px = [p.real for p in f] -ox = (max(px) + min(px)) / 2.0 -py = [p.imag for p in f] -oy = (max(py) + min(py)) / 2.0 -fo = ox + oy * 1j -ss = 0.0 -for i in range(len(f)): -    if i == len(f) - 1: -        j = 0 -    else: -        j = i + 1 -    a = abs(f[i] - fo) -    b = abs(f[j] - fo) -    c = abs(f[j] - f[i]) -    z = (a + b + c) / 2.0 -    s = math.sqrt(z * (z - a) * (z - b) * (z - c)) -    ss += s -print(("%.6f" % ss)) + +def area_polygon(points): +    area = 0 +    n = len(points) +    for i in range(n): +        area += cross(points[i], points[(i + 1) % n]) +    return area / 2 + + +import sys + +p = [] +for line in sys.stdin: +    x, y = list(map(float, line.split(","))) +    p.append(complex(x, y)) +print((area_polygon(p)))