#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>
#include<random>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, -1, 0, 1};
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

bool solve(string s) {
    reverse(s.begin(), s.end());
    int n = s.size();
    if (n < 3) return false;
    int cnt = 0;
    bool flag = false;
    for (int i = 0; i < n; i++) {
        if (s[i] == 'R') cnt++;
        else if (s[i] == 'G') {
            if (--cnt < 0) return false;
            flag = true;
        } else {
            if (!flag) return false;
        }
    }
    if (cnt) return false;
    reverse(s.begin(), s.end());
    cnt = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == 'W') cnt++;
        else if (s[i] == 'G') {
            if (--cnt < 0) return false;
        }
    }
    return true;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int T;
    cin >> T;
    while (T--) {
        string s;
        cin >> s;
        if (solve(s)) cout << "possible" << endl;
        else cout << "impossible" << endl;
    }
    return 0;
}