int state = 0;
int btn = 7;
int LB = btn;
const int led = 5;
void setup() {
  Serial.begin(9600);
 pinMode(btn, INPUT_PULLUP);
 pinMode(led, OUTPUT);
}

void loop() {
  int btnState = digitalRead(7);
  if (btnState == 1 && LB == 0) {
    state = !state;
    digitalWrite(led, state);
  } 
  Serial.print(btnState);
  Serial.print(LB);
  delay(250);
}