int lastButtonState;
int pushButton = 3;
int buttonState ;
int ledState = 1;

void setup() {
pinMode(pushButton,INPUT);  
pinMode(13,OUTPUT);
Serial.begin(9600);
}

void loop() {
buttonState = digitalRead (pushButton);
Serial.print(buttonState);
if(buttonState == 0 & lastButtonState == 1)
{
digitalWrite(13,ledState);
ledState = 1- ledState;
delay(200);

}
lastButtonState = buttonState;
}