Difficult communication with processing

@jremington , here it is:

const int buttonPin1 = 1;
const int buttonPin2 = 2;
const int buttonPin3 = 3;
const int buttonPin4 = 4;
const int buttonPin5 = 5;
const int buttonPin6 = 6;
const int buttonPin7 = 7;
const int buttonPin8 = 8;
const int buttonPin9 = 9;
const int buttonPin10 = 10;
const int buttonPin11 = 11;
const int buttonPin12 = 12;
const int buttonPin13 = 13;


// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status
int incomingByte;


void setup() {
  // initialize the LED pin as an output:
  Serial.begin(9600);
  
  pinMode(ledPin, OUTPUT); // l'output doit être une data envoyée a processing  Serial.begin(9600);
  // initialize the pushbutton pin as an input:
  
  pinMode(buttonPin1, INPUT);
  pinMode(buttonPin2, INPUT);
  pinMode(buttonPin3, INPUT);
  pinMode(buttonPin4, INPUT);
  pinMode(buttonPin5, INPUT);
  pinMode(buttonPin6, INPUT);
  pinMode(buttonPin7, INPUT);
  pinMode(buttonPin8, INPUT);
  pinMode(buttonPin9, INPUT);
  pinMode(buttonPin10, INPUT);
  pinMode(buttonPin11, INPUT);
  pinMode(buttonPin12, INPUT);
  pinMode(buttonPin13, INPUT);
  
  
 }
 

void loop() {
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin1);
  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == HIGH) {
    // turn LED on:
    Serial.write('A'); //quelque chose a la place de "ledpin"
  } else {
    // turn LED off:
    Serial.write('L');
  }


  buttonState = digitalRead(buttonPin2);
 if (buttonState == HIGH) {
    Serial.write('B');
    
  } else {
    
    Serial.write('L');
  }
  
  
  
   buttonState = digitalRead(buttonPin3);
   
   if (buttonState == HIGH) {
   
    Serial.write('C'); 
  } else {
   
    Serial.write('L');
  }

   buttonState = digitalRead(buttonPin4);
   
   if (buttonState == HIGH) {
 
    Serial.write('D');
  } else {

    Serial.write('L');
  }

   buttonState = digitalRead(buttonPin5);
   
   if (buttonState == HIGH) {
  
    Serial.write('E');
  } else {
   
    Serial.write('L');
  }

   buttonState = digitalRead(buttonPin6);
   
   if (buttonState == HIGH) {
 
    Serial.write('F'); 
  } else {
   
    Serial.write('L');
  }

  
   
   buttonState = digitalRead(buttonPin7);
   
   if (buttonState == HIGH) {
   
    Serial.write('G'); 
  } else {
 
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin8);
   
   if (buttonState == HIGH) {
    
    Serial.write('H');
  } else {
 
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin9);
   
   if (buttonState == HIGH) {
   
    Serial.write('I'); 
  } else {
   
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin10);
   
   if (buttonState == HIGH) {
   
    Serial.write('J'); 
  } else {
    // turn LED off:
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin11);
   
   if (buttonState == HIGH) {
    
    Serial.write('K'); 
  } else {
    
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin12);
   
   if (buttonState == HIGH) {
    
    Serial.write('M'); 
  } else {
   
    Serial.write('L');
  }

  buttonState = digitalRead(buttonPin13);
   
   if (buttonState == HIGH) {
    
    Serial.write('N'); 
  } else {
    
    Serial.write('L');
  }
}