#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef _MSC_VER
#pragma warning(disable:4996)
#endif

int BinToCh(char* bin)
{
    int ch = 0;
    int i = 0;
    int val = 1;

    for(i=4; i>=0; i--)
    {
        if(bin[i] == '1')
        {
            ch += val;
        }
        val *= 2;
    }
    if(ch > 0 && ch < 27)
    {
        return ch + ('A' - 1);
    }
    else
    {
        return ' ';
    }
}

char* Trim(char* buf, int len)
{
    char* temp;
    char* end;
    char* start;
    temp =(char*)calloc(len + 1, sizeof(char)); 

    strcpy(temp, buf);
    end = temp + strlen(temp) - 1;

    while(end != temp && *end == ' ')
    {
        end--;
    }
    *(end + 1) = '\0';

    start = temp;

    while(start != (temp + strlen(temp) - 1) && *start == ' ')
    {
        start++;
    }

    strcpy(buf, start);
    free(temp);

    return buf;
}

int main(int argc, char** argv)
{
    int n = 0;
    int i = 0;
    int j = 0;
    int k = 0;
    int row = 0;
    int col = 0;
    int R = 0;
    int C = 0;
    size_t idx = 0;
    size_t l = 0;
    int cnt = 0;
    char string[401] = {0, };
    char plaintext[401] = {0, };
    char* ans;
    char matrix[21][21] = {0, };
    char cipher[401] = {0,};

    scanf("%d", &n);

    for(i=0; i<n; i++)
    {
        idx = 0;
        cnt = 0;
        row = 0;
        col = 0;
        scanf("%d %d %s", &R, &C, cipher);

        for(j=0; j<21; j++)
        {
            for(k=0; k<21; k++)
            {
                matrix[j][k] = '\0';
            }
        }

        for(j=0; j<R; j++)
        {
            for(k=0; k<C; k++)
            {
                matrix[j][k] = cipher[j*C + k];
            }
        }

        while(idx < strlen(cipher))
        {

            if(idx == 0)
            {

            }
            else if(R == 1)
            {
                col++;
            }
            else if(C == 1)
            {
                row++;
            }
            else if(col == (C - 1) && row != (R - 1))
            {
                row++;
            }
            else if(row == (R - 1) && col != cnt)
            {
                col--;
            }
            else if(col == cnt && row != cnt)
            {
                row--;
            }
            else
            {
                col++;
            }

            if(row == cnt && col == cnt && idx > 1)
            {
                row++;
                col++;
                R--;
                C--;
                cnt++;
            }

            string[idx++] = matrix[row][col];
        }

        for(l=0; l<strlen(string)/5; l++)
        {
            plaintext[l] = BinToCh(string + 5*l);
        }
        plaintext[l] = '\0';
        ans = Trim(plaintext, strlen(plaintext));

        printf("%d %s\n", (i+1), ans);
        memset(string, 0, strlen(string));
        memset(plaintext, 0, strlen(plaintext));
    }
}