#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;
#define al(a) a.begin(), a.end()
#define ral(a) a.rbegin(), a.rend()
#define sz(a) (int)a.size()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define db(a, b) cout << #a << ": " << a << " " << #b << ": " << b << endl;

int main() {
  int t;
  cin >> t;
  rep(ti, t) {
    string s;
    cin >> s;
    int n = sz(s);
    bool ok = true;
    bool preW = false;
    int g = 0, r = 0;
    drep(i, n) {
      if (s[i] == 'W') {
        if (!g || !r) ok = false;
        preW = true;
      }
      else {
        if (preW) {
          g--, r--;
          preW = false;
        }
        if (s[i] == 'G') {
          g++;
          if (g > r) ok = false;
        }
        if (s[i] == 'R') { r++; }
      }
    }
    if (preW) {
      g--, r--;
      preW = false;
    }
    if (g || r) ok = false;

    if (ok)
      cout << "possible\n";
    else
      cout << "impossible\n";
  }
  return 0;
}