int redPin=12;
int greenPin=11;
int bluePin=10;
String mycolor;
String msg=("what is your led color ?");
int DT=500;
void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
Serial.println(msg);{
while(Serial.available()==0)
mycolor= Serial.readString();
if (mycolor=="red")
digitalWrite(redPin, HIGH);
digitalWrite(greenPin, LOW);
digitalWrite(bluePin, LOW);
if (mycolor=="green")
digitalWrite(greenPin, HIGH);
delay(500);
digitalWrite(redPin, LOW);
digitalWrite(bluePin, LOW);
if(mycolor=="blue")
digitalWrite(bluePin, HIGH);
digitalWrite(greenPin, LOW);
digitalWrite(redPin, LOW);
delay(DT);
}
}