int L = 5;
int B = 10;
int Bstate = LOW;
int Lstate = LOW;
int lastBstate;

void setup() {
	pinMode(B, INPUT);
	pinMode(L, OUTPUT);
}

void loop() {

	Bstate = digitalRead(B);

	if (Bstate == HIGH && lastBstate == LOW) {

		Lstate = !Lstate;

		digitalWrite(L, Lstate);
	}

	lastBstate = Bstate;

	delay(50);
}