#include<bits/stdc++.h>

int n, m;
char s1[55], s2[55];
int a[105][105];
int p[105];
bool check[105];

bool dfs(int x)
{
    for(int i = 1; i <= 2 * m; i++)
        if (a[x][i])
        {
            if (!check[i]) 
            {
                check[i] = true;
                if (p[i] == 0 || dfs(p[i]))
                {
                    p[i] = x;
                    p[x] = i;
                    return true;
                }
            }
        }
    return false;
}

int main()
{
    int T;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d%d", &n, &m);
        memset(a, 0, sizeof(a));
        for(int j = 1; j <= m; j++)
            for(int k = 1; k <= m; k++)
                a[j][m + k] = a[m + k][j] = 1; 
        for(int i = 1; i <= n; i++)
        {
            
            scanf("%s", s1);
            scanf("%s", s2);
            for(int j = 0; j < m; j++)
                for(int k = 0; k < m; k++)
                    if (s1[j] != s2[k]) 
                        a[j + 1][m + k + 1] = a[m + k + 1][j + 1] = 0;
        }
        
        //hungary
        int ans = 0;
        memset(p, 0, sizeof(p));
        for(int i = m; i >= 1; i--)
        {
            if (!p[i])
            {
                memset(check, false, sizeof(check));
                if (dfs(i)) ans++;
            }
        }
        
        if (ans < m) printf("-1");
        else
        {
            printf("%d", p[1] - m);
            for(int i = 2; i <= m; i++) printf(" %d", p[i] - m);
        }
        printf("\n");
    }
    return 0;
}