Stop print from scrolling

[highway61ie]

@highway61ie

void loop() {
    /* verify that there is no error in detecting the image from the camera */
    if (!capture_still()) {
        Serial.println("Failed capture");      
        return;
    }
// the following allows to count the number of people according to the direction of their movement 
   switch (motion_detect()){
    case 0 : 
      Serial.println("no motion");
      list[1]=0;
      digitalWrite(12, LOW);
      digitalWrite(4, LOW);
      break;  
    case 1 : 
      Serial.println("get in "); // when a person gets in that means that he is coming from the left side( the motion is detected from the left side of the photo) 
      list[1]= 1;
      digitalWrite(12, HIGH);
      digitalWrite(4, LOW);
      break; 
    case -1 : 
      Serial.println("get out"); // when a person gets out that means that he is coming from the right side( the motion is detected from the right side of the photo) 
      list[1]= -1 ;
      digitalWrite(12, LOW);
      digitalWrite(4, HIGH);
      break;       
   }
 // if two directions or more are detected simultaneously (within milliseconds) only the first one will be selected     
    if ((list[0]==0) && (list[1]==1)){
       counter= counter+1 ; // if the person is getting in the building +1 is added 
    }else if ((list[0]==0) && (list[1]==-1)){
        counter=counter-1 ; //if the person is getting out the building 1 is substracted
       }
       
    Serial.print(counter) ; 
    list[0]= list[1]; //the current value will be the preview value
    Serial.println("=================");
    update_frame();
      

}

First of thanks guys for the reply ..At least now I don't feel so alone with this problem .
I knew thought the hardest part of this was going to be getting across exactly what the problem is In the loop there are three possible outputs . "No Motion" , "Get In" and "Get out" . No motion is always = to Zero . Get in = plus one and get out = minus one . All good so far . The last serial.println("======"); gives the output to the serial monitor .But as it's a loop each time it loops it prints the Value to the serial port so I get a continuous stream of data (mostly Zeros ) .All I'm interested in is the total number e.g. 100 people approach the camera from the right so they are plus 100 . Meanwhile 25 people approach from the left so they are minus 25 . This leaves the total at number of 75 . The sketch will happilly run and give the correct numbers but meanwhile I have a serial output about a mile long with each loop repeating . I think what I need is a way to tell the last seral.println firstly to ignore the zeros and secondly not to print if the previous number generated by the previous loop hasn't changed . Most of the answers to similar questions to this seem to only involve two possible scenarios i.e. turn a switch on or off and then use an int to store the previous value e.g. below but how to do this with my three options

int old_something;

void loop ()
{
int something = get_my_data ();
if (something != old_something)
Serial.print (something); // display if it changed
old_something = something;
}