#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<vector>
#define pb push_back
#define mp make_pair
#define xx first
#define yy second
#define rep(i,a,b) for(int i=(a),i##_end_=(b);i<=i##_end_;i++)
#define dwn(i,a,b) for(int i=(a),i##_end_=(b);i>=i##_end_;i--)
using namespace std;
inline int read() {
    int x=0,f=1;char c=getchar();
    for(;!isdigit(c);c=getchar()) if(c=='-') f=-1;
    for(;isdigit(c);c=getchar()) x=x*10+c-'0';
    return x*f;
}
typedef long long ll;
typedef pair<int,int> pii;
const int N=55;
int n,m,tim;
int vis[N],match[N],ans[N];
int ok[N][N];
bool dfs(int x) {
    rep(y,1,m) if(ok[x][y]) {
        if (vis[y]==tim) continue;
        vis[y]=tim;
        if (!match[y] || dfs(match[y])) {
            match[y]=x;
            return 1;
        }
      }
      return 0;
}
char A[N],B[N];

void solve() {
      n=read();m=read();
      memset(match,0,sizeof(match));
      rep(i,1,m) rep(j,1,m) ok[i][j]=1;
     rep(i,1,n) {
        scanf("%s%s",A+1,B+1);
        rep(j,1,m) rep(k,1,m) if(A[j]!=B[k]) ok[j][k]=0;
    }
      dwn(i,m,1) {
        ++tim;
        if (!dfs(i)) {
          puts("-1");
          return;
        }
      }
      rep(i,1,m) ans[match[i]]=i;
      rep(i,1,m) printf("%d%c",ans[i],i==m?'\n':' ');
}
int main() {
    int T=read();
    while(T--) solve();
    return 0;
}