x=input("请输入斤数：")
if x<6:
y=5*x
else:
y=5*x*0.8
print(y)

x=eval(input("请输入斤数："))
if x<6:
y=5*x
else:
y=5*x*0.8
print(y)

x=eval(input("请输入斤数："))
if x<6:
y=5*x*0.8
else:
y=5*x
print(y)

x=input("请输入斤数：")
if x<6:
y=5*x*0.8
else:
y=5*x
print(y)