Heron's formula Calculation Program

This is a program to find the area of a triangle from the length of three sides using Heron's formula.
* about Heron's formula

Heron's formula

The area of a triangle(S) with sides of length a, b, c is :

where

You can input Integer, fraction, and decimal. Values must be larger than 0.
Number of characters that can be input, is 7.Number of characters that can be input, is 7.

About fraction input:

• For ex, "2/3"(two thirds) - please input "2" first, and "/", "3".
• In case of mixed number fraction - for ex "3+4/5".

At each processing, an internal calculation uses the value in which the sixth place of the decimal point is rounded up when cannot it be done after it converts it into the decimal, and it be divided even if it is an input by the fraction.