it works but need to refiine it a bit

What i need to do:

The factorial of a non-negative integer n is written n! (pronounced "n factorial") and is defined as follows:

n! = n * (n-1) * (n-2) * ... * 1 (for values of n greater than or equal to 1)

and

0! = 1

For example 5! = 5*4*3*2*1, which is equal to 120.

Write a program that inputs a non-negative integer and computes and prints its factorial. Use a "while loop" as part of your program implementation. only between 0 and 12 .

Code:#include <stdio.h> int main() /* Function main begins program execution */ { int integern; /* Integer n to be evaluated */ int counter; /* Integer entered */ int result; /* Factorial of integer */ int start; /* beginning of execution */ start: printf( "Input value to compute factorial for:\n" ); /* Prompt input value for n */ scanf( "%d", &integern ); /* Obtained integer value */ /* Initialization phase */ result = 1; /* Intitialize result */ counter = integern; /* Initialize loop counter */ /* Processing phase */ while ( counter > 1 ) { /* Loop until counter equals 1 */ result = result * counter; /* Multiply counter to result */ --counter; /* decrement counter */ } /* If integer greater or 0, print "factorial is equal to: %d" */ if ( integern >= 0 ) printf( "\nFactorial is equal to:%d\n", result ); /* otherwise, print "Input value not valid." */ else{ printf( "\nError: Input value not valid.\n\n"); goto start; } return 0; /* Indicate program ended successfully */ } /* Ends function main */