#include <stdio.h>
 #include "pico/stdlib.h"

 #define DEBOUNCE 200  // define debounce is 200

 int main() {
 unsigned int gpio , ogpio , fmgpio ; // initialise the variables
 unsigned int led_pins = 0xfc; // initialise all led's
 unsigned int sw_pin = 15; // initialise switch y as pin 15 on its own
 for (gpio = 12; gpio < 15; gpio ++) { // set up other switches
 gpio_init(gpio);
 gpio_set_dir(gpio , GPIO_IN);
 gpio_pull_up(gpio);
 }
  gpio_init(sw_pin); // set up switch y
 gpio_set_dir(sw_pin, GPIO_IN);
 gpio_pull_up(sw_pin);
  for (gpio = 2; gpio < 8; gpio ++) { // set up led's
 gpio_init(gpio);
 gpio_set_dir(gpio , GPIO_OUT);
 }
 
 while (1) {
 for (gpio = 12; gpio <15; gpio ++)
 {
 ogpio = gpio - 10; // ogpio value or formula
 fmgpio = ogpio + 3; // fmgpio value or formula

 gpio_put(ogpio , !gpio_get(gpio)); // turn on the led's that are a consequence of the formula for ogpio
 gpio_put(fmgpio , !gpio_get(gpio)); // turn on the led's that are a consequence of the formula for fmgpio

  if (!gpio_get(sw_pin)) // if statement , if switch y is pressed then:
{
    gpio_put_masked(led_pins, 0xfc); // turn on all LED's
}
else{ // else statment
sleep_ms(DEBOUNCE);// turn off all LED's when switch y is released
}
 }

 }
 }