#include <bits/stdc++.h>
using namespace std;
const int maxn = 55;
int n,m;
int p[maxn][maxn],ans[maxn],linker[maxn],used[maxn];
char s[maxn],t[maxn];
bool dfs(int u) {
    for (int v=1;v<=m;v++) if (p[u][v] && !used[v]) {
        used[v] = true;
        if (linker[v] == 0 || dfs(linker[v])) {
            linker[v] = u;
            return true;
        }
    }
    return false;
}
int main(void) {
//    freopen("b.in","r",stdin);
    int T; scanf("%d",&T);
    while (T--) {
        scanf("%d%d",&n,&m);
        for (int i=1;i<=m;i++) for (int j=1;j<=m;j++) p[i][j]=1;
        for (int i=0;i<n;i++) {
            scanf("%s%s",s+1,t+1);
            for (int j=1;j<=m;j++) {
                for (int k=1;k<=m;k++) {
                    if (s[j]!=t[k]) p[j][k]=0;
                }
            }
        }
        for (int i=1;i<=m;i++) linker[i]=0;
        int ok = 1;
        for (int i=m;i>=1;i--) {
            memset(used,0,sizeof(used));
            if (!dfs(i)) {ok=0; break;}
        }
        if (ok == 0) { printf("-1\n"); continue; }
        for (int i=1;i<=m;i++) ans[linker[i]] = i;
        for (int i=1;i<=m;i++) printf("%d%c",ans[i]," \n"[i==m]);
    }
    return 0;
}