int boton = 2;
int ledRojo = 3;
int ledVerde = 4;

void setup() {
  pinMode(boton, INPUT_PULLUP);
  pinMode(ledRojo, OUTPUT);
  pinMode(ledVerde, OUTPUT);
}

void loop() {
  if (digitalRead(boton) == HIGH) {
    digitalWrite(ledRojo, HIGH);
    digitalWrite(ledVerde, LOW);
  } else {
    digitalWrite(ledRojo, LOW);
    digitalWrite(ledVerde, HIGH);
  }
}