#include <iostream>
#include <fstream>
using namespace std;

long long ton(char c)
{
  if (c>='0'&&c<='9') return c-'0';
  else if (c>='a'&&c<='f') return c-'a'+10;
  return 0;
}

long long toll(string &s)
{
  long long ret=0;
  for (int i=0;i<s.length();i++)
    ret=ret*16+ton(s[i]);
  return ret;
}

int main()
{
  ifstream cin("C.txt");

  int cases;cin>>cases;
  while(cases--){
    long long dat[9];
    for (int i=0;i<9;i++){
      string s;cin>>s;
      dat[i]=toll(s);
    }

    long long ans=0;
    int carry=0;
    for (int i=0;i<32;i++){
      int sum=carry;
      for (int j=0;j<8;j++)
	sum+=(dat[j]>>i)&1;
      int check=(dat[8]>>i)&1;

      int p=((check&1)==(sum&1))?0:1;
      ans|=(p<<i);
      
      sum=carry;
      for (int j=0;j<8;j++)
	sum+=((dat[j]>>i)&1)^p;
      carry=sum>>1;
    }
    cout<<hex<<(ans&0xFFFFFFFF)<<endl;
  }

  return 0;
}