#include<bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
#define ls i<<1
#define rs ls | 1
#define mid ((ll+rr)>>1)
#define pii pair<int,int>
#define MP make_pair
typedef long long LL;
const long long INF = 1e18+1LL;
const double Pi = acos(-1.0);
const int N = 5e5+10, M = 1e3+20, mod = 1e9+7, inf = 2e9;

int head[N],t,cas = 1;
struct ss{
    int to,next;
    LL value;
}e[N*2];
int vis[N],cnt,T,n,m;
LL dep[N],ins[N],a[N];
void add(int u,int v,LL w) {
    e[t].next = head[u];
    e[t].to = v;
    e[t].value = w;
    head[u] = t++;
}
void dfs(int u,int f) {
    vis[u] = vis[f] + 1;
    for(int i = head[u]; i; i = e[i].next) {
        int to = e[i].to;
        if(to == f || (vis[to] && vis[to] < vis[u])) continue;
        if(vis[to]) {
            a[++cnt] = e[i].value ^ dep[to] ^ dep[u];
            continue;
        }
        dep[to] = dep[u] ^ e[i].value;
        dfs(to,u);
    }
}
int main() {
    scanf("%d",&T);
    while(T--) {
        scanf("%d%d",&n,&m);
        memset(head,0,sizeof(head));
        memset(vis,0,sizeof(vis));
        memset(dep,0,sizeof(dep));
        memset(ins,0,sizeof(ins));
        t = 1;
        cnt = 0;
        for(int i = 1; i <= m; ++i) {
            int u,v;LL w;
            scanf("%d%d%I64d",&u,&v,&w);
            add(u,v,w);
            add(v,u,w);
        }
        dfs(1,0);
        for(int i = 1; i <= cnt; ++i) {
            for(int j = 62; j >= 0; --j) {
                if(a[i]&(1LL<<j)) {
                    if(!ins[j]) {
                        ins[j] = a[i];
                        break;
                    }
                    a[i] ^= ins[j];
                }
            }
        }
        LL ans = 0;
        for(int i = 62; i >= 0; --i) {
            if((ins[i]^ans) > ans) ans^=ins[i];
        }
        printf("Case #%d: %I64d\n",cas++,ans);
    }
    return 0;
}