#include <iostream>
#include <cmath>

char process_c(char c, int *e_count)
{
    switch (c)
    {
    case 'J':
        // 可以是J，D
        *e_count += 1;
        return 'J';

    case 'B':
        // 必须是 D
        return 'D';

    case 'D':
    default:
        // 可以是J，D
        *e_count += 1;
        return 'J';
    }
}

/*
long long quick_power(int base, long long exp){
    long long result = 1;
    while (exp > 0)
    {
        if (exp % 2 == 1)
        {
            result *= base;
        }
        base *= base;
        exp /= 2;
        
    }
    
}
*/

long long int_power(int base, long long exp){
    long long result = 1;
    for (int i = 0; i < exp; i++)
    {
        result *= base;
    }
    return result;
}

long long case_result()
{
    int char_count;
    std::cin >> char_count;

    std::string s;
    std::string s_opposite;
    int e_count = 0;
    long long solution_count = 0;
    std::cin >> s;

    if (s.back() != 'J')
    {
        return 0;
    }
    s.pop_back();

    // 先计算积攒最多能量的方法
    for (char c : s)
    {
        s_opposite += process_c(c, &e_count);
    }
    // std::cout << s_opposite << ' ';

    if (e_count < 1)
    {
        return 0;
    }
    else
    {
        solution_count = int_power(2, e_count) - 1;
    }

    return solution_count;
}

int main()
{
    int cases_count;
    std::cin >> cases_count;

    for (int i = 0; i < cases_count; i++)
    {

        std::cout << case_result() << std::endl;
    }

    return 0;
}