help about NFC shield programming

i need to make a program that will deduct 3 each time the button is pressed. I can’t get my program right. how can i fix it. below is my sample code.pls help me because this is for my project :frowning: there is no error while compling but when i run the program it only deduct a load once

void loop(){

sensorState = digitalRead(2);
while(sensorState == 1);

       if(sensorState == 0){
            uint32_t id;
            id = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A);
                 if (id != 0){

                  uint8_t keys[]= {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
                  uint8_t writeBuffer[16];
                  uint8_t block[16];
                  nfc.authenticateBlock(1, id ,0x08,KEY_A,keys);
                  load = block[0];
                  writeBuffer[0] = load - 3;  


Dear customer,

Glad to know you sharing your program here, but sorry that we not solve software.
But might be other people can help you.

Best regards,