int led=12;
int button=2;
int val=0;
int old_val=0;
int state=0;

void setup ()
{
pinMode(led,OUTPUT);
pinMode(button,INPUT);

}

void loop()
{ val=digitalRead(button);
if( (val==HIGH) && (old_val==LOW)) {
state=1-state;}
old_val=val;
if (state==1)
 { 
  
  digitalWrite(led, HIGH);}
else {

  digitalWrite (led,LOW);}

}