Controlling a Servo Motor and a DC motor from the Serial Monitor

I am trying to create a robot with one DC motor for movement and one servo motor for steering using an Arduino Uno. The servo is simply connected to pin 9, and the DC motor is connected to pin 10 through a Mosfet (see attached diagram). I was hoping that when I type an “L” or an “R” in the serial monitor the Servo moves to a certain position, and when type a number between 0 and 255, the DC motor rotates at that speed. So far I have the code to make the Servo turn, according to numbers entered into the Serial monitor and the same for the DC motor. How would I make the Servo respond to letters and how would I make them work from the same code?
Here is the code for the DC Motor:

int motorControlPin = 10;                                                                   
void setup() {
  pinMode(motorControlPin, OUTPUT);                                                        
  Serial.begin(9600);                                                                      
  Serial.println("Enter a Value between 0-255 to set the speed of the motor");             
}

void loop() 
{
  if (Serial.available())                                                                   
   {
    int speed = Serial.parseInt();                                                         
    analogWrite(motorControlPin, speed);                                                   
   }
}

Here is the code for the Servo:

#include <Servo.h>

Servo servo1;  
long num;     

void setup()
{
 servo1.attach(9);
Serial.begin(9600); 
Serial.print("Enter Position = ");
}

void loop() 
{ 
  while(Serial.available()>0)
  { 
  num= Serial.parseInt();   
  Serial.print(num);  
  Serial.println(" degree");
  Serial.print("Enter Position = ");
  }
  servo1.write(num);
  delay(15);
}

How would I make the Servo respond to letters and how would I make them work from the same code?
Here is the code for the DC Motor:

The simplest way is to change the protocol. Can you imagine what TL means? What TR means? What S123 means? If so, you can easily see that the first letter indicates which motor to diddle with. Parsing the rest of the string then depends on the first letter.