a = float(input("nota 1: "))
b = float(input("nota 2: "))
c = float(input("nota 3: "))
d = float(input("nota 4: "))
p1 = 1
p2 = 2
p3 = 3
p4 = 4
mp = (a*p1) + (b*p2) + (c*p3) + (d*p4)
fn = p1+p2+p3+p4
total = (mp/fn)
print(round(total, 2))