Honda door unlock rolling code

#include <stdio.h>

int main(){
  int code[4];
  int i;
  int A = 0x7;
  int B = 0xB;
  int C = 0xD;
  int D = 0xE;
  int R = 0xF;
  int S = 0x5;
  int a = 0x7;
  int b = 0x3;
  int c = 0x8;
  int d = 0x2;
  int r = 0x6;
  int s = 0x9;
  
  code[0] = A;
  code[1] = B;
  code[2] = C;
  code[3] = D;
  
  for (i=0; i<4; i++){
    code[i] = (code[i] + A + B + C + D + R + S) & 0xF;
  }
  
  for (i=0; i<4; i++){
    if (code[i] == 10