#include <iostream>
#include <string>

void solve() {
    std::string s;
    std::cin >> s;

    int cnt = 0;
    for (char c : s) {
        if (c == 'G') {
            ++cnt;
        } else if (c == 'R') {
            --cnt;
            if (cnt < 0) {
                std::cout << "impossible" << std::endl;
                return;
            }
        }
    }

    std::cout << (cnt == 0 ? "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;
}