def museumAdmissionFee(adults, seniors, children):
    total = 6
    n = 1.0
    while n<children:
        n+=1
        total+=6*.9**(n-1)
    if children<=0:
        total=0

    return float(total + adults + seniors)

c=float(input ('How many children?: '))
a=float(input ('How many adults?:   '))*10
s=float(input ('How many seniors?:  '))*7

print ('Price for entrance',museumAdmissionFee(a, s, c),'$')
input()