#include <iostream>
#include <string>
#include <vector>
#include <algorithm>


bool solve(const std::string s) {
    int slen = s.length();
    int cntG = std::count_if(s.begin(), s.end(), [](char c) { return c == 'G'; });
    int cntR = std::count_if(s.begin(), s.end(), [](char c) { return c == 'R'; });
    int cntW = slen - (cntG + cntR);

    if (cntG != cntR || cntW < cntG || slen < 3 || s[0] != 'W') return false;

    int cnt = cntG;
    cntG = 0;
    cntR = 0;

    bool is_possible = true;
    for (const auto& c : s) {
        if (c == 'W') {
            if (cnt < 1) {
                is_possible = false;
                break;
            }
        } else if (c == 'G') {
            cntG++;
            cnt--;
        } else if (c == 'R') {
            cntR++;
            if (cntG < cntR) {
                is_possible = false;
                break;
            }
        }
    }

    return is_possible;
}


int main(int argc, char const* argv[]) {
    int T;
    std::cin >> T;

    std::vector<std::string> s(T);
    for (int i = 0; i < T; i++) {
        std::cin >> s[i];
    }

    for (int i = 0; i < T; i++) {
        std::cout << (solve(s[i]) ? "possible" : "impossible") << std::endl;
    }
    return 0;
}