[URGENT] Statistical Calculator

I really need help on this for my exercise, I do not wish to see any losses mark. I beg someone could help me to solve this. By the way, i am just a college student. Maybe this sounds easy to me but I'm just a beginner. I need a simple C++ program. HELP PLEASE.

Question
Statistical Calculator
Write a program to read in a sequence of examination mark from a text file named as input.txt and produce the mean, and standard deviation of the marks. Your program should also produce a bar chart for each grade where the range of mark is given as below.

Grade Marks Range
A 80-100
B 70-79.9
C 50-69.9
D 40-49.9
F 0-39.9

Output the result to another text file named as output.txt.

There is not limitation for the interface or menu design. Be innovative and creative!!

THANK YOU!
not-a-native-english-speaker

Um...no. You have to make an effort yourself.

Just to clarify what GCDEF already wrote:
Can you help me with my homework assignment?

I'm sorry for making troubles here. I've solved it. Thank You