a = input().split(",")
s = 0
for i in range(0 , len(a)-2 , 2):
    ans = ((int(a[i + 2]) - int(a[i]))**2 + (int(a[i + 3]) - int(a[i + 1]))**2)**0.5
    s += ans
s += ((0 - int(a[1]))**2 + (0 - int(a[0]))**2)**0.5
print("%.2f" % s)