int led1=3;
int led2=4;
int led3=5;
int led4=6;
int led5=7;
int led6=8;
int led7=9;
int a;
int mode=1;
int keep=HIGH;
int zhongduanpin=2;
int count=1;
void onchange(){
  if(digitalRead(zhongduanpin)==LOW){
    delay(500);
    if(digitalRead(zhongduanpin)==LOW){
      while(!digitalRead(zhongduanpin)){
        
        
      }
      count++;

    }
  }
}
void setup() {
  for(a=3;a<10;a++)
  pinMode(a , OUTPUT);
  pinMode(10, INPUT_PULLUP);
  Serial.begin(9600);
  pinMode(zhongduanpin, INPUT);
  attachInterrupt(digitalPinToInterrupt(zhongduanpin),onchange,FALLING);
}
void loop() {
  mode=count;
  for(a=3;a<10;a+=mode){
    digitalWrite(a , HIGH);
    delay(500);
  }
  for(a=9;a>2;a-=mode){
    digitalWrite(a,LOW);
    delay(500);
  }
}