def museumAdmissionFee(a,b,c):
    return float(a+b+c)

c=float(input ('How many children?: '))
a=float(input ('How many adults?:   '))*10
s=float(input ('How many seniors?:  '))*7
n=1.0
cTotal=6

while n<c:
    n+=1
    cTotal+=6*.9**(n-1)
if c<=0:
    cTotal=0

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