A program for judging the result of cyclic input

  I don't say much nonsense , Go straight to the code ：

i =5  # Definition i
while i>2:
    i = i-1  # Satisfy while Condition rule i reduce 1
    a = eval(input(" Please enter the grade ："))
    if a<0 or a>100 or a%1 != 0:
        print(" The score you entered is unreasonable , Please check and re-enter ")

    elif 90 <= a <= 100:
        print(" Your grade ：A")

    elif 80<= a < 90:
        print(" Your grade ：B")

    elif 70<= a < 80:
        print(" Your grade ：C")

    elif 60<= a < 70:
        print(" Your grade ：D")

    else:
        print(" Your grade ：E")

The operation results are as follows ：

 Please enter the grade ：90
 Your grade ：A
 Please enter the grade ：60
 Your grade ：D
 Please enter the grade ：40
 Your grade ：E
>>> 

The knowledge points are as follows ：

1：while Syntax and usage of sentences ：

while <condition> Conditional statements :
    <execute statement> Execute statement 

 Parameter description 

condition： For conditional statements , Used to set the conditions of the loop , Can be equal to 、 Comparison, etc . such as a==3、a>2. When conditions are TURE namely while true Represents an infinite loop .

execute statement： Execute statement , That is, what needs to be executed after the cycle conditions are met .

2：eval() Function will formula character string Convert to formula