PROGRAMMING:grade point
###Task description
```
Peking University implements GPA system for undergraduates. The actual test scores of students are calculated according to different credits of different subjects according to a certain formula.
The formula is as follows:
Actual GPA
90——100 4.0
85——89 3.7
82——84 3.3
78——81 3.0
75——77 2.7
72——74 2.3
68——71 2.0
64——67 1.5
60——63 1.0
Below 60 0
1. GPA of a course = GPA of the course * credit of the course
2. Total GPA = sum of all subject GPA / sum of all course credits
Now you are asked to write a program to find someone's GPA.
```
###Input format:
```
The total number of courses in the first row is n (n < 10);
The second line is the credits of corresponding courses (the two credits are separated by spaces);
The third line is the actual score of the corresponding course;
All numbers entered here are integers.
```
###Output format:
```
Output has a line, the total score point, accurate to 2 decimal places after the decimal point（ printf("%.2f",GPA);）
```
###Input example:
```in
five
4 3 4 2 3
91 88 72 69 56
```
###Output example:
```out
two point five two
```
###Title Source
Selected from openjudge website, online address: http://sdau.openjudge.cn/c/078/
answer：If there is no answer, please comment
```
Peking University implements GPA system for undergraduates. The actual test scores of students are calculated according to different credits of different subjects according to a certain formula.
The formula is as follows:
Actual GPA
90——100 4.0
85——89 3.7
82——84 3.3
78——81 3.0
75——77 2.7
72——74 2.3
68——71 2.0
64——67 1.5
60——63 1.0
Below 60 0
1. GPA of a course = GPA of the course * credit of the course
2. Total GPA = sum of all subject GPA / sum of all course credits
Now you are asked to write a program to find someone's GPA.
```
###Input format:
```
The total number of courses in the first row is n (n < 10);
The second line is the credits of corresponding courses (the two credits are separated by spaces);
The third line is the actual score of the corresponding course;
All numbers entered here are integers.
```
###Output format:
```
Output has a line, the total score point, accurate to 2 decimal places after the decimal point（ printf("%.2f",GPA);）
```
###Input example:
```in
five
4 3 4 2 3
91 88 72 69 56
```
###Output example:
```out
two point five two
```
###Title Source
Selected from openjudge website, online address: http://sdau.openjudge.cn/c/078/
answer：If there is no answer, please comment