#include <Arduino.h>


char counter = 0;
void setup() {
  //configure output pin as 0
  pinMode(10, OUTPUT);
  digitalWrite(10, 0);
  
  //configure input pins to be inputs
  pinMode(1, INPUT);
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(4, INPUT);
  
}

void loop() {
  
  if (digitalRead(1) && digitalRead(2) && !digitalRead(3) && !digitalRead(4) && (counter == 0))  // first code received is 1100
  { 
    counter = 1;
  }
  
  if ( !digitalRead(1) && digitalRead(2) && digitalRead(3) && !digitalRead(4) && (counter == 1))  // second code received is 0110
  {
    counter = 2;
  }
  
  if (!digitalRead(1) && !digitalRead(2) && digitalRead(3) && digitalRead(4) && (counter == 2))  // third code received is 0011
  {
    counter = 3;
  }
  
  if (counter == 3)  // turn on the output pin 10
  {
    digitalWrite(10, 1);
    
  }
  
  if (!digitalRead(1) && digitalRead(2) && digitalRead(3) && digitalRead(4) && (counter == 3))  // turn off output pin 10,  code received is 0111
  {
    digitalWrite(10, 0);
    counter = 0;
  }
  
}

if (digitalRead(input1)==HIGH && digitalRead (input2) == HIGH) && digitalRead (input3) == LOW && digitalRead (input4) == LOW

Byte InputValue =0;
.
.
.
 )if(digitalRead(input1)==HIGH
{InputValue=1}
)if (digitalRead(input2)==HIGH
{InputValue=InputValue+2}
)if (digitalRead(input3)==HIGH
{InputValue=InputValue+4
if (digitalRead(input4)==HIGH
{InputValue=InputValue+8