#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned ll
#define endl "\n"
#define PII pair<int,int>
const ll INF=0x3f3f3f3f;//3f3f3f3f;
const int mod=1e9+7;
const int N=2e6+5;
bitset<1035>f[2][1035];
void solve(){
	int n,m; cin>>n>>m;
	for(int i=1;i<2055;i++) f[0][i].reset();
	f[0][0][0]=1;
	int cur=1,lst=0;
	for(int i=1;i<=n;i++){
		int v,w; cin>>v>>w;
		for(int j=0;j<1024;j++) f[cur][j]=f[lst][j];
		for(int j=0;j<1024;j++){
			f[cur][j]|=f[lst][j^w]<<v;
		} swap(lst,cur);
	}
	int ans=1023;
	while(ans>=0&&!f[lst][ans][m]) ans--;
	cout<<ans<<endl;
}
int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int T=1; cin>>T;
    while(T--) solve();
}