from machine import Pin
from time import sleep

# Inputs
S1 = Pin(26, Pin.IN, Pin.PULL_UP)
S2 = Pin(27, Pin.IN, Pin.PULL_UP)
S3 = Pin(14, Pin.IN, Pin.PULL_UP)

# Outputs
greenLED = Pin(2, Pin.OUT)
redLED = Pin(4, Pin.OUT)

while True:

    # Read buttons
    # Pressed = 1, Released = 0
    s1 = 1 - S1.value()
    s2 = 1 - S2.value()
    s3 = 1 - S3.value()

    # Default state: LOCKED
    greenLED.off()
    redLED.off()

    #