#include <iostream>
#include <algorithm>
#include <vector>
#include <numeric>
#include <queue>
#include <string>
using namespace std;

bool solve(string s) {
    int n = s.size();
    int W = count(s.begin(), s.end(), 'W');
    int G = count(s.begin(), s.end(), 'G');
    int R = count(s.begin(), s.end(), 'R');
    if (W == 0 || G == 0 || R == 0 || G != R || s[0] != 'W' || s[n - 1] != 'R') {
        return false;
    }
    vector<int> used(n);
    int w = 0;
    int g = n - 2;
    int r = n - 1;
    while (1) {
        while (r >= 0 && (!used[r] && s[r] != 'R')) --r;
        if (r < 0) break;
        g = r - 1;
        while (g >= 0 && (!used[g] && s[g] != 'G')) --g;
        if (g < 0) break;
        w = g - 1;
        while (w >= 0 && (!used[w] && s[w] != 'W')) --w;
        if (w < 0) break;
        used[r] = used[g] = used[w] = true;
        --r;
    }

    g = n - 1;
    while (g >= 0 && s[g] != 'G') --g;
    for (int i = 0; i < n; ++i) {
        if (s[i] == 'W' && i >= g) {
            return false;
        }
        if ((s[i] == 'R' || s[i] == 'G') && !used[i]) {
            return false;
        }
    }
    return true;
}


int main() {
    int t;
    cin >> t;
    for (int i = 0; i < t; ++i) {
        string s;
        cin >> s;
        puts(solve(s) ? "possible" : "impossible");
    }
}