text: #include <stdio.h>
  #include <stdlib.h>
  
  // -------------------------------solution begin-------------------------------
  int hammingDistance(int x, int y) {
    return __builtin_popcount(x ^ y);
  }
  // -------------------------------solution end---------------------------------
  
  int main(int argc, char const *argv[]) {
    int input1 = 1, input2 = 4;
    printf("Input:  %d, %d\n", input1, input2);
    printf("Output: %d\n", hammingDistance(input1, input2));
    return EXIT_SUCCESS;
  }
  