void setup() {
  int a = 2;
  int m;
  while (a < 7)  
  {
  pinMode(a, OUTPUT);
  pinMode(m, OUTPUT);
  a++ ;
  }

}
 int a = 2;
 int m =6;
void loop() {
  // put your main code here, to run repeatedly:

 int t=400;
  while (a <= 6 ) {
    digitalWrite(a, HIGH);
    digitalWrite(m, HIGH);
    delay(t);
    digitalWrite(a, LOW);
    digitalWrite(m, LOW);
    delay(t);
    a++;
    m--;
    if (a==2){t=800;}
    if (a==3){t=1000;}
    if (a==4){t=800;}
    if (a==5){t=400;}
    if (a==6){t=400;}
  }
 
 }