Roomba robot Arduino source

#include <Servo.h>

Servo servo1;
Servo servo2;
const int m1_p1 = 3;
const int m1_p2 = 5;
const int m2_p1 = 6;
const int m2_p2 = 11;

void setup() {
  pinMode(m1_p1,OUTPUT);
  pinMode(m1_p2,OUTPUT);
  pinMode(m2_p1,OUTPUT);
  pinMode(m2_p2,OUTPUT);
  pinMode(A0,OUTPUT);
  pinMode(A1,OUTPUT);
  digitalWrite(m1_p1,LOW);
  digitalWrite(m1_p2,LOW);
  digitalWrite(m2_p1,LOW);
  digitalWrite(m2_p2,LOW);
  Serial.begin(9600);
  servo1.attach(A0 );
  servo2.attach(A1);
}

void loop() {
  if (Serial.read() == 'c' ) {
    delay(5);
    int a = Serial.parseInt();
    int b = Serial.parseInt();
    int s1 = Serial.parseInt();
    int s2 = Serial.parseInt          ();
    int motor1_value = constrain(a,0,255);
    int motor2_value = constrain(b,0,255);
    Serial.write(10);
    int m1_p1_value = constrain(motor1_value - 128,0,128)*2;
    int m1_p2_value = constrain(motor1_value,0,127)*2;
    if (m1_p1_value != 0 && m1_p2_value != 0)
        m1_p2_value = 0;
    int m2_p1_value = constrain(motor2_value - 128,0,128)*2;
    int m2_p2_value = constrain(motor2_value,0,127)*2;
    if (m2_p1_value != 0 && m2_p2_value != 0)
        m2_p2_value = 0;
    servo1.write(s1);
    servo2.write(s2);
    analogWrite(m1_p1,m1_p1_value);
    analogWrite(m1_p2,m1_p2_value);
    analogWrite(m2_p1,m2_p1_value);
    analogWrite(m2_p2,m2_p2_value);
  }
}