URI 1051

a = float(input())

if(0 < a < 2000):
    print("Isento")
elif(2000 < a <= 3000):
    b = a - 2000
    c = b * 0.08
    print("R$ %.2f" %(c))
elif(3000 < a < 4500):
    b = a - 3000
    c = (b * 0.18) + (1000 * 0.08)
    print("R$ %.2f" %(c))
else:
    b = a - 4500
    c = (b * 0.28) + (1500 * 0.18) + (1000 * 0.08)
    print("R$ %.2f" %(c))