int red = 5; //red led at pin 
int green = 6; //green led at pin
int blue = 7; //blue led at pin 
int redswitch = 8; //reading of switch at pin 8
int greenswitch = 9; //reading of switch at pin 9
int blueswitch = 10; //reading of switch at pin 10
int counter; //counts
int redtimer = 500; //length of red light's flashing
int greentimer = 700; //length of green light's flashing
int bluetimer = 900; //length of blue light's flashing

void setup() {
  // put your setup code here, to run once:
  pinMode(red,OUTPUT);
  pinMode(green,OUTPUT);
  pinMode(blue,OUTPUT);
  pinMode(redswitch,INPUT);
  pinMode(greenswitch,INPUT);
  pinMode(blueswitch,INPUT);
  counter = 0;
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(redswitch) == HIGH) {
    if (((counter / redtimer) % 2) == 0) {
      digitalWrite(red,HIGH);
    } else {
      digitalWrite(red,LOW);
    }
  } else {
    digitalWrite(red,LOW);
  }

  if (digitalRead(greenswitch) == HIGH) {
    if (((counter / greentimer) % 2) == 0) {
      digitalWrite(green,HIGH);
    } else {
      digitalWrite(green,LOW);
    }
  } else {
    digitalWrite(green,LOW);
  }

  if (digitalRead(blueswitch) == HIGH) {
    if (((counter / bluetimer) % 2) == 0) {
      digitalWrite(blue,HIGH);
    } else {
      digitalWrite(blue,LOW);
    }
  } else {
    digitalWrite(blue,LOW);
  }
  
  counter = counter + 1;
  delay(1);
}