How to do 3 part if statement in python?

Why the if statements doesnt work at the below? I just want if the values are number do the math, if the values are string except "Done" give me just "enter a number" warning and continue, if the value is "Done" finish the job and give me the answers.

quantity = 0
sum = 0
avg = 0
n = None


while n != "Done":
    try:
        n = int(input("Enter a value:\n"))
        sum = sum + n
        quantity = quantity + 1
        avg = sum / quantity
    except:
        print("Enter a number!")

        if n =="Done":
            print("Process is Done!")
            break
            print("Sum : {}, Quantity : {}, Avg : {}".format(sum, quantity,avg))