// Nothing is Given, Everything is Earned.
#include<bits/stdc++.h>
using namespace std;

int main()
{
   int T; cin>>T;
   while(T--)
   {
      static const int N=1024;
      int n,m,a[n+1],b[n+1];
      bitset<N> f[n+1][n+1];
      scanf("%d%d",&n,&m);
      for(int i=1;i<=n;i++) scanf("%d%d",a+i,b+i);
      f[0][0][0]=1;
      for(int i=1;i<=n;i++)
      {
         for(int j=0;j<1024;j++)
         {
            f[i][j]=(f[i-1][j]|f[i-1][j^b[i]]<<a[i]);
         }
      }
      int ans=-1;
      for(int i=1023;~i;i--)
      {
         if(f[n][i][m]) ans=max(ans,i);
      }
      cout<<ans<<endl;
   }
   return 0;
}