int led1=2;
int led2=3;
int led3=4;
int led4=5;

int Dec;
int Bin;

void setup() {
pinMode(led1,OUTPUT);
pinMode(led2,OUTPUT);
pinMode(led3,OUTPUT);
pinMode(led4,OUTPUT);

}

void loop() {

for(Dec=0;Dec<=16;Dec++){
delay(1000);

if(Dec==0){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}

else if(Dec==1){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==2){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}
else if(Dec==3){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==4){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==5){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}
else if(Dec==6){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}
else if(Dec==7){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==8){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==9){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==10){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}

else if(Dec==11){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==12){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==13){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==14){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}


else if(Dec==15){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}

}


//Down count

for(Dec=16;Dec>=0;Dec--){
delay(1000);

if(Dec==0){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}

else if(Dec==1){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==2){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}
else if(Dec==3){
  digitalWrite(led1,0);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==4){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==5){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}
else if(Dec==6){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}
else if(Dec==7){
  digitalWrite(led1,0);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==8){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==9){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==10){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}

else if(Dec==11){
  digitalWrite(led1,1);
  digitalWrite(led2,0);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}
else if(Dec==12){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,0);
}
else if(Dec==13){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,0);
  digitalWrite(led4,1);
}

else if(Dec==14){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,0);
}


else if(Dec==15){
  digitalWrite(led1,1);
  digitalWrite(led2,1);
  digitalWrite(led3,1);
  digitalWrite(led4,1);
}}

}