What is incorrect about my code? Please keep it simple like I have it here.

	* Accept a string such as "varTwo = 5 - theBestVar"
	* Convert the string to a line in which the camel case substrings are
	converted to snake style substrings.
	* display the string
	* please name your java source file as CamelToSnake.java
	*
	* Note: if there are multiple Uppercase letters, then split the
	* string so that the last capital character is part of the
	* next word. For example WCURams would become wcu_rams
	*
	* For example:
	* Example 1:
	* input: varTwo = 5 - theBestVar
	* output: var_two = 5 - the_best_var
	* Example 2:
	* input: CMMaxLength = INMaxLength / 2.54
	* output: cm_max_length = in_max_length
	public class CamelToSnake {
	String lowerstring = "";
	char A = str.charAt(0);
	lowerstring = lowerstring + Character.toLowerCase(a);
	for (int i=1; i
	char ch = str.charAt(i);
	if(Character.isUpperCase(ch)) {
	lowerstring = lowerstring + Charcter.toLowerCase(ch);
	}
	else {
	lowerstring = lowerstring + ch;
	}
	}
	return lowerstring;
	}
	public static void main(String[] args) {
	// program starts running here.
	}
	System.out.println(CamelToSnake(string));
	}