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

void solve() {
    std::string s;
    std::cin >> s;
    std::reverse(s.begin(), s.end());

    int wcnt = 0, gcnt = 0, rcnt = 0, gok = 0;
    for (char c : s) {
        if (c == 'W') {
            ++wcnt;
            gok = std::max(0, gok - 1);
        } else if (c == 'G') {
            ++gok;
            ++gcnt;
        } else if (c == 'R') {
            ++rcnt;
        }

        if ((gcnt == 0 && wcnt > 0) || gcnt > rcnt) {
            std::cout << "impossible" << std::endl;
            return;
        }
    }

    std::cout << (gok == 0 && gcnt == rcnt ? "possible" : "impossible")
              << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    int q;
    std::cin >> q;
    while (q--) solve();

    return 0;
}