#define RED_LED 13
#define BLUE_LED 14
#define PB 21


void setup() {
 pinMode(BLUE_LED, OUTPUT);
 pinMode(RED_LED, OUTPUT);
 pinMode(PB, INPUT_PULLUP);
}

void loop() {

  
 
 digitalWrite(RED_LED, HIGH);
 for(int i=0;i<1000;i++){
 toggle();
 delay(1);
 }
 digitalWrite(RED_LED, LOW);
 for(int i=0;i<1000;i++){
 toggle();
 delay(1);
 }
}

void toggle(){
 if(digitalRead(PB)==LOW){
 while(digitalRead(PB)==LOW){
 delay(25);
 }
 digitalWrite(BLUE_LED,!digitalRead(BLUE_LED));
}
}