#include <Servo.h>
Servo servo1;
Servo servo2;
Servo servo3;
Servo servo4;
Servo servo5;
Servo servo6;
int i;
int j;

void setup() {
  // put your setup code here, to run once:
servo1.attach(3);
servo2.attach(4);
servo3.attach(5);
servo4.attach(6);
servo5.attach(7);
servo6.attach(8);
servo1.write(45);
servo2.write(45);
servo3.write(45);
servo4.write(45);
servo5.write(45);
servo6.write(45);

}

void loop() {
  // put your main code here, to run repeatedly:
forward(1);
delay(1000);
forward(2);
}

void forward(int group){
  if (group == 1){
    for (i; i <= 45; i++){
      servo1.write(45 + i);
      servo3.write(45 + i);
      servo5.write(45 - i);
      delay(20);
    }
    i = 0;
  } else if (group == 2){
    for (j; j <= 45; j++){
      servo2.write(45 + j);
      servo4.write(45 + j);
      servo6.write(45 - j);
      delay(20);
  }
  j = 0;
  }
}