#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 2147483647
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    int t;
    int w, g, r,f;
    cin >> t;
    for (int i = 0; i < t; i++)
    {
        string s;
        cin >> s;
        w = g = r = f = 0;
        bool miss = false;
        for (int j = 0; j < s.length(); j++)
        {
            switch (s[j]) {
                case 'W':
                    w++;
                    f = 1;
                    break;
                case 'G':
                    if (w <= g) {
                        miss = true;
                    }
                    else {
                        g++;
                        if (f = 1) f++;
                    }
                    break;
                case 'R':
                    if (g <= r) {
                        miss = true;
                    }
                    else {
                        r++;
                        if (f = 2) f++;
                    }
                    break;
            }
            if (miss) break;
        }
        if (miss || g != r || g == 0 || f != 3) cout << "impossible" << endl;
        else cout << "possible" << endl;
    }
    getchar(); getchar();
    return 0;
}