pseudocode about registers and clients

Question

I have projects that requires to simulate a market with 3 registers. Every second an amount of clients come to the registers and we assume that each clients takes 4 seconds to the register before he leaves. Now lets suppose that we get an input of all the customers and their arriving time: e.x: 0001122334455 which means that 3 customers enter at second 0, 2 at second 1 etc. What i need to find is the total time which need to serve all the customers now matter how many they are and also to find the average waiting time at the store.

Can someone come up with a pseudocode for this problem?

  while(flag){
  while(i<A.length-1){
  if(fifo[tail].isEmpty()) fifo[tail].put(A[i] +4);
  else{
  temp= fifo[tail].peek();
  fifo[tail].put(A[i]-temp+4);
  i++;
  }
  if(tail == a-1){
   tail=0;
  }else tail++;
  if(i>3){
  for(int q =0; q<a; q++){
  temp = fifo[q].peek();
  if(temp==i){
  fifo[q].get();
  }
  }   
  }
  }


 }

where A is the array which contains all the customers as numbers as required from the input, and fifo is the array of the registers with the get , put and peek(get the tail but not remove it) methods. I have no clue though how to find the total time an the average waiting time