def c1():
    print("C = " , (a**2 + b**3)/(a-b))

def c2():
    print("C = " , (a + 3*b + a*b)/(4-a*b)**2)

def c3():
    print("C = " , ((3*(a+b))/2*b) + (3*a/(6*a - (b**3))))

def c4():
    print("C = " , (5*a) + (2*a**2)/(1 + (3*b) / (1 + (5*b+1) / a)))

while(True):
    a , b , x = map(int , input().split())
    
    if(x == 1):
        c1()
    elif(x == 2):
        c2()
    elif(x == 3):
        c3()
    elif(x == 4):
        c4()
    else:
        print("x may be 1 or 2 or 3 or 4")