/* Thu Nov 25 15:19:14 JST 2004 */
/* Thu Nov 25 15:55:29 JST 2004 */
#include <stdio.h>

unsigned int N[9];

unsigned int mask_bit[32], summ_bit[32];

int main()
{
  int S, iS;
  int i, j;
  unsigned int bit, K, sum[2];

  bit = 0x00000001;
  for (i = 0; i < 32; i++) {
    mask_bit[i] = bit;
    if (i > 0) { summ_bit[i] = summ_bit[i-1] + mask_bit[i]; }
    else       { summ_bit[i] = mask_bit[i]; }
    bit <<= 1;
  }

  scanf("%d", &S);
  for (iS = 0; iS < S; iS++) {
    for (i = 0; i < 9; i++) { scanf("%x", &N[i]); } if (feof(stdin)) { break; }
    K = 0;
    for (i = 0; i < 32; i++) {
      sum[0] = sum[1] = 0;
      for (j = 0; j < 8; j++) {
        sum[0] += (N[j] & summ_bit[i]) ^ (K);
        sum[1] += (N[j] & summ_bit[i]) ^ (K | mask_bit[i]);
      }
      /*      printf("%8x:%8x   ", sum[0], sum[1]); */
      if ((sum[0] & summ_bit[i]) == ((N[8] ^ (K              )) & summ_bit[i])) {
        /*        printf("!"); */
      }
      if ((sum[1] & summ_bit[i]) == ((N[8] ^ (K | mask_bit[i])) & summ_bit[i])) {
        /*        printf("?"); */
        K |= mask_bit[i];
      }
    }
    printf("%x\n", K);
  }
  return 0;
}