int button1 = 2;  
int button2 = 3;  
int lamp = 4;     

void setup() {
  pinMode(button1, INPUT_PULLUP); 
  pinMode(button2, INPUT_PULLUP);
  pinMode(lamp, OUTPUT);           

  digitalWrite(lamp, LOW);       
}

void loop() {

  if (digitalRead(button1)== LOW && digitalRead(button2)== HIGH) {
    digitalWrite(lamp, HIGH);  
  } else if (digitalRead(button1) == HIGH && digitalRead(button2) == LOW) {
    digitalWrite(lamp, LOW);   
  }
}