const int led = 12;
const int Sw = 5;
int i = 0;

void setup() 
{
  pinMode(Sw, INPUT);
  pinMode(led, OUTPUT);
}

void loop() 
{
int val=digitalRead(Sw);
 if(val == HIGH)
 {
     i++;
     delay(300);
     if (i == 1){
       digitalWrite(led, HIGH);
     }
}
if(i == 2)
    {
    digitalWrite(led, LOW);
    i=0;
    }
}