2-dimensional array

Hi,

I am trying to visualize a bass neck using 2-dimensional arrays.
If the input equals A, every A on the bass neck should change from 1 to 0.
But if I run the code in attachment it does not work…

int i = 0;
int j = 0;
int nek[13][4];

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  for(j=0;j<13;j++){
  for(i=0;i<4;i++){
      nek[i][j] = 1;
  }
 }
}

void loop() {
  // put your main code here, to run repeatedly:

  if(Serial.available()){

    int val = Serial.read();
  
    
    switch(val){
      case 65:
      nek[1][0]=0;
      //nek[0][5]=0;
      //nek[2][7]=0;
      //nek[3][2]=0;

      Serial.print('\n');
      Serial.println("A:");

      Serial.print('\n');
      for(j=0;j<13;j++){
       for(i=0;i<4;i++){
          Serial.print(nek[i][j]);
          Serial.print(" ");
       }
      Serial.print('\n');
      }
      
      break;
      
      case 66:
      Serial.println("B:");
      break;
      
      case 67:
      Serial.println("C:");
      break;
      
      case 68:
      Serial.println("D:");
      break;
      
      case 69:
      Serial.println("E:");
      break;
      
      case 70:
      Serial.println("F:");
      break;
      
      case 71:
      Serial.println("G:");
      break;
    }
  }     
}

It always changes 2 places from 1 into 0. (output shown in attachment)
Can anyone see wath I am doing wrong?

Thanks!

int nek[13][4];

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  for(j=0;j<13;j++){
  for(i=0;i<4;i++){
      nek[i][j] = 1;

Your indices are reversed.

That was a stupid mistake...

Thanks!