with open(r'day9/input.txt', 'r') as input:
    lines = list(map(lambda x: list(map(lambda y: int(y),x.split(','))),input.read().split('\n')[:-1]))

def surface(a,b):
    return (abs(a[0]-b[0])+1)*(abs(a[1]-b[1])+1)

best = surface(lines[0],lines[1])

for i in range(len(lines)):
    for j in range(i):
        best = max(best,surface(lines[i],lines[j]))

print(best)