#include <Button.h>
Button btn(13);

const byte led1 = 7;
const byte led2 = 8;
const byte led3 = 9;
const byte led4 = 10;

// Use 4 elements because easier to ref LED1 to nextime[1] (0 based counting)
unsigned long nextTime[4];
int ledState = 0;
byte stopFlag = 0;

int btnState = 0;
void setup() {
  pinMode(led1,OUTPUT);
  pinMode(led2,OUTPUT);
  pinMode(led3,OUTPUT);
  pinMode(led4,OUTPUT);
  digitalWrite(led1,LOW);
  digitalWrite(led2,LOW);
  digitalWrite(led3,LOW);
  digitalWrite(led4,LOW);
  btn.begin();
}

void loop() {
  // put your main code here, to run repeatedly:
  if(millis() >= nextTime[1] && stopFlag == 0){ // If LED4 is off, blink every 1.2 seconds
    nextTime[1] = millis() + 1200;
    ledState = !digitalRead(led1);
    digitalWrite(led1,ledState);
  }
    if(millis() >= nextTime[2]){
    nextTime[2] = millis() + random(200,800);
    ledState = !digitalRead(led2);
    digitalWrite(led2,ledState);
  }
    if(millis() >= nextTime[3]){
    nextTime[3] = millis() + random(400,1200);
    ledState = !digitalRead(led3);
    digitalWrite(led3,ledState);
  }
  if(btn.pressed()){
    digitalWrite(led4,!digitalRead(led4));
    stopFlag = !stopFlag;
    digitalWrite(led1,LOW);
  }
}